The voltage-gated proton (Hv1) channel is crucial in regulating cellular pH, yet the mechanism underlying proton permeation remains controversial. A deeper understanding of the differences between the channel's active and resting states is essential for clarifying its conductive properties. In this study, we employ a combination of molecular dynamics simulations, site-directed mutagenesis, and electrophysiological recordings to investigate what changes occur in an active Hv1 channel and how these changes influence conduction properties in the wild-type (WT) channel, a low-conducting N264R mutant, and a superconductive N264E mutant. Our findings reveal that in the active state, interactions are weakened between the selectivity filter, aspartate D160, and the third arginine in the S4 transmembrane segment. This results in a more negatively charged and hydrated environment, which enables proton transport in the WT and N264E channels. Notably, these conformational changes are absent in the N264R mutant. Additionally, our simulations predict-and osmotic shock experiments in oocytes confirm-that an active Hv1 channel can facilitate water permeation. These observations suggest that water conduction occurs as a byproduct of a more dilated and hydrated pathway. We introduce a methodological approach to studying Hv1 by utilizing water permeation as a functional readout. Collectively, our results provide insights into the structural rearrangements of the Hv1 constriction zone, shedding light on how its resting and active configurations govern proton conduction.

Aquaporins (AQPs) are membrane proteins specialized in facilitating water transport across membranes. Mechanical stress is one of the various stimuli that regulate AQPs. Briefly, there are several studies that report a decrease in permeability upon an increase in membrane tension. However, the molecular details of this mechanosensitive (MS) response are still a matter of debate. Our work attempts to close that gap in knowledge by providing evidence of a conformational change that occurs inside the pore of the strawberry aquaporin FaPIP2;1. Via osmotic shock experiments and molecular dynamics (MD) simulations, we found that a residue of loop B, I106, is key to the blocking of the permeation pathway and such a change is almost exclusively found under membrane tensile stress. In detail, osmotic shock experiments exhibited a nonlinear increment in water fluxes for increasing osmolarities, evidencing a decrease in the FaPIP2;1 permeability. MD simulations under membrane tension showed the same trend, with a significant increase in states with a low water permeability. The latter was correlated with a conformational change in I106 that generates a permeation barrier of around 18 kJ mol-1, effectively closing the pore. This work constitutes the first report of a PIP type aquaporin reacting to tensile stress in the membrane. Our findings could pave the way to test whether this conformational change is also responsible for mechanical gating in the other MS aquaporins, both those already reported and those still waiting to be found.

The majority of voltage-gated ion channels contain a defined voltage-sensing domain and a pore domain composed of highly conserved amino acid residues that confer electrical excitability via electromechanical coupling. In this sense, the voltage-gated proton channel (Hv1) is a unique protein in that voltage-sensing, proton permeation and pH-dependent modulation involve the same structural region. In fact, these processes synergistically work in concert, and it is difficult to separate them. To investigate the process of Hv1 voltage sensor trapping, we follow voltage-sensor movements directly by leveraging mutations that enable the measurement of Hv1 channel gating currents. We uncover that the process of voltage sensor displacement is due to two driving forces. The first reveals that mutations in the selectivity filter (D160) located in the S1 transmembrane interact with the voltage sensor. More hydrophobic amino acids increase the energy barrier for voltage sensor activation. On the other hand, the effect of positive charges near position 264 promotes the formation of salt bridges between the arginines of the voltage sensor domain, achieving a stable conformation over time. Our results suggest that the activation of the Hv1 voltage sensor is governed by electrostatic–hydrophobic interactions, and S4 arginines, N264 and selectivity filter (D160) are essential in the Ciona-Hv1 to understand the trapping of the voltage sensor.

Previous studies on monomeric N264R showed that the OFF-gating current is completely trapped and that, from a kinetic point of view, this charge displacement takes a long time to return. Currently, the molecular mechanism governing this entrapment of charge remains unknown. In order to understand the OFF-gating charge trapping mechanism, we performed patch-clamp in its inside-out configuration using Xenopus laevis oocytes as a heterologous expression system, combined with molecular dynamics and kinetic modeling. Our results shows that the ΔNΔC D160N mutant does not have a trapped charge at the OFF-gating charge; but, when the N264R mutation is added to this mutant, the OFF-gating charge trapping appears in a diminished state. This is possibly because the residue in position 160, which is also the selectivity filter of the channel, interacts with the arginines of the voltage sensor. In addition, the 2GBI blocker possesses a guanidinium group which also presents an arginine in its side chain. This inhibitor generates an effect similar to ΔNΔC N264R OFF-gating charge displacement. This suggests that arginine is required for charge trapping. By performing mutations at position 160 it was found that hydrophobicity near that position obstructs the movement of the voltage sensor exerting an effect similar to that of the aromatic rings of 2GBI. Furthermore, when ΔpH is increased and especially when acidity is increased on the intracellular side, the OFF-gating charge is also trapped. We performed molecular dynamics simulations on ΔNΔC N264R, and our results suggest that the positive charge of arginine “push-up” the arginines 258 and 261 and form a stable salt-bridge over time with D160. Finally, our results confirm that for the gating charge to be trapped it is necessary to change the electrostatic configuration on the intracellular side near position 264.

The acid-base characteristics of tumor cells and the other elements that compose the tumor microenvironment have been topics of scientific interest in oncological research. There is much evidence confirming that pH conditions are maintained by changes in the patterns of expression of certain proton transporters. In the past decade, the voltage-gated proton channel (Hv1) has been added to this list and is increasingly being recognized as a target with onco-therapeutic potential. The Hv1 channel is key to proton extrusion for maintaining a balanced cytosolic pH. This protein-channel is expressed in a myriad of tissues and cell lineages whose functions vary from producing bioluminescence in dinoflagellates to alkalizing spermatozoa cytoplasm for reproduction, and regulating the respiratory burst for immune system response. It is no wonder that in acidic environments such as the tumor microenvironment, an exacerbated expression and function of this channel has been reported. Indeed, multiple studies have revealed a strong relationship between pH balance, cancer development, and the overexpression of the Hv1 channel, being proposed as a marker for malignancy in cancer. In this review, we present data that supports the idea that the Hv1 channel plays a significant role in cancer by maintaining pH conditions that favor the development of malignancy features in solid tumor models. With the antecedents presented in this bibliographic report, we want to strengthen the idea that the Hv1 proton channel is an excellent therapeutic strategy to counter the development of solid tumors.

Voltage-gated proton channels (Hv1) are important regulators of the immunosuppressive function of myeloid-derived suppressor cells (MDSCs) in mice and have been proposed as a potential therapeutic target to alleviate dysregulated immunosuppression in tumors. However, till date, there is a lack of evidence regarding the functioning of the Hvcn1 and reports on mHv1 isoform diversity in mice and MDSCs. A computational prediction has suggested that the Hvcn1 gene may express up to six transcript variants, three of which are translated into distinct N-terminal isoforms of mHv1: mHv1.1 (269 aa), mHv1.2 (269 + 42 aa), and mHv1.3 (269 + 4 aa). To validate this prediction, we used RT-PCR on total RNA extracted from MDSCs, and the presence of all six predicted mRNA variances was confirmed. Subsequently, the open-reading frames (ORFs) encoding for mHv1 isoforms were cloned and expressed in Xenopus laevis oocytes for proton current recording using a macro-patch voltage clamp. Our findings reveal that all three isoforms are mammalian mHv1 channels, with distinct differences in their activation properties. Specifically, the longest isoform, mHv1.2, displays a right-shifted conductance–voltage (GV) curve and slower opening kinetics, compared to the mid-length isoform, mHv1.3, and the shortest canonical isoform, mHv1.1. While mHv1.3 exhibits a V0.5 similar to that of mHv1.1, mHv1.3 demonstrates significantly slower activation kinetics than mHv1.1. These results suggest that isoform gating efficiency is inversely related to the length of the N-terminal end. To further explore this, we created the truncated mHv1.2 ΔN20 construct by removing the first 20 amino acids from the N-terminus of mHv1.2. This construct displayed intermediate activation properties, with a V0.5 value lying intermediate of mHv1.1 and mHv1.2, and activation kinetics that were faster than that of mHv1.2 but slower than that of mHv1.1. Overall, these findings indicate that alternative splicing of the N-terminal exon in mRNA transcripts encoding mHv1 isoforms is a regulatory mechanism for mHv1 function within MDSCs. While MDSCs have the capability to translate multiple Hv1 isoforms with varying gating properties, the Hvcn1 gene promotes the dominant expression of mHv1.1, which exhibits the most efficient gating among all mHv1 isoforms.

Cellular systems must deal with mechanical forces to satisfy their physiological functions. In this context, proteins with mechanosensitive properties play a crucial role in sensing and responding to environmental changes. The discovery of aquaporins (AQPs) marked a significant breakthrough in the study of water transport. Their transport capacity and regulation features make them key players in cellular processes. To date, few AQPs have been reported to be mechanosensitive. Like mechanosensitive ion channels, AQPs respond to tension changes in the same range. However, unlike ion channels, the aquaporin’s transport rate decreases as tension increases, and the molecular features of the mechanism are unknown. Nevertheless, some clues from mechanosensitive ion channels shed light on the AQP-membrane interaction. The GxxxG motif may play a critical role in the water permeation process associated with structural features in AQPs. Consequently, a possible gating mechanism triggered by membrane tension changes would involve a conformational change in the cytoplasmic extreme of the single file region of the water pathway, where glycine and histidine residues from loop B play a key role. In view of their transport capacity and their involvement in relevant processes related to mechanical forces, mechanosensitive AQPs are a fundamental piece of the puzzle for understanding cellular responses.

Ultrasound is very useful in the management of rheumatological pathology today. Despite this, in Colombia, progress towards its implementation is limited and entails great difficulties. This deficit is also related to the difficulties in training new human talent. In Colombia, there is no study that identifies the current status of ultrasound among rheumatologists in the country.This is a descriptive cross-sectional study where medical specialists in Rheumatology practising in Colombia were surveyed through an online form. They were asked about general aspects and for their opinion regarding ultrasound in rheumatology and, if they practiced it, they were asked about specific aspects of its application in clinical practice. Additionally, questions were asked of the rheumatologists who are part of the specialist training processes in the country. Closed multiple-choice or Likert scale assessment questions were presented as required. The main objective was to describe the current use and opinion of musculoskeletal ultrasound in Colombian rheumatologists, as well as the limitations for its implementation. Frequency measurements were performed of the categorical variables of nominal type and ordinal type. The intention was to survey all rheumatologists in the country, who according to Colombian Society of Rheumatology data for the end of 2019 totalled 186.Taking into account the number of rheumatologists of the Colombian Association of Rheumatology (Asoreuma) for 2019 totalling 186, a participation of 139 specialists (74.7%) was obtained, of which 22 of the respondents performed ultrasound in their daily practice (15.8%) the majority in this group being trained in Colombian territory (80.6%). Of the 139 respondents, 64.7% have received some type of training in ultrasound, generally pre-congress courses (22.5%), EULAR courses (16.7%) and training included in their residency curriculum outside the rheumatology service (9.8%). The acceptance of ultrasound is high among rheumatologists practicing in Colombia, 75.5% consider it important or very important and 84.9% indicated that for a comprehensive rheumatology service it is important or very important to have ultrasound. From the responses, however, they consider that its use could change their behaviour frequently, and very frequently in less than half of the cases at 46.7%. Regarding the opinion on the use of ultrasound in specific pathologies, rheumatoid arthritis (77.7%) and crystal arthropathies (72.7%) were considered the highest and most important, as well as in the performance of procedures at 87%. For decision-making in the inflammatory pathology study, 60.4% would consider performing ultrasound compared to 28.8% who responded MRI. Regarding the limitations for implementation, the lack of training in the country (25.6%), followed by the lack of resources to procure equipment (17.9%) and ignorance and lack of interest on the part of the health entities (17.1%) were the most recognized.Musculoskeletal ultrasound is only practiced by a minority of rheumatologists practicing in Colombia, even though the majority consider it important. Its importance lies in its use to treat patients with rheumatoid arthritis, crystal arthropathies and psoriatic arthropathy, as well as for the performance of procedures. More than half of the rheumatologists have received some type of training in ultrasound, usually very few hours’ education and without practical or informal training, this being the main problem for its implementation.En la actualidad la ecografía es de gran utilidad en el manejo de la patología reumatológica. A pesar de esto, en Colombia los avances para su implementación son escasos y han enfrentado grandes dificultades. Este déficit también se encuentra relacionado con las dificultades para la formación del nuevo talento humano. En Colombia no se dispone de ningún estudio en el que se identifique el estado actual de la ecografía entre los reumatólogos del país.Se trata de un estudio descriptivo de carácter transversal en el cual se encuestó, por medio de un formulario on-line, a médicos especialistas en reumatología que hacen su práctica en el territorio colombiano. Se les preguntó acerca de los aspectos generales y su opinión sobre la ecografía en la reumatología, si la practicaban, como también en torno a los aspectos específicos de su aplicación en la práctica clínica. De forma adicional, se formularon preguntas dirigidas a aquellos reumatólogos que hacen parte de los procesos de formación de especialistas en el país; se presentaron preguntas cerradas de opción múltiple o de valoración por escala de Likert según se requiera. El objetivo principal fue describir el uso y la opinión actual sobre la ecografía musculoesquelética en reumatólogos colombianos, así como las limitantes para su implementación. A las variables categóricas de tipo nominal y de tipo ordinal se les hicieron medidas de frecuencia. Se pretendía encuestar a la totalidad de los reumatólogos en el país, los cuales según información de la Asociación Colombiana de Reumatología (Asoreuma) de finales del 2019 eran 186.De acuerdo con el número de reumatólogos proporcionado por Asoreuma, de 186 especialistas en el año 2019, se obtuvo una participación de 139 de estos (74,7%), de los cuales 22 realizaban ecografía en su práctica diaria (15,8%), siendo este grupo en su mayoría formado en Colombia (80,6%). De los 139 encuestados, el 64,7% había recibido algún tipo de formación en ecografía, generalmente cursos precongreso (22,5%), cursos EULAR (16,7%) y formación incluida en el pensum de su residencia fuera del servicio de reumatología (9,8%). La aceptación de la ecografía es alta entre los reumatólogos que ejercen en Colombia, el 75,5% la consideraron importante o muy importante. Asimismo, el 84,9% indicó que para un servicio de reumatología integral es importante o muy importante contar con ecografía. Sin embargo, los encuestados consideraron que su uso podría llegar a cambiar su conducta de forma frecuente, y muy frecuentemente en menos de la mitad de los casos (46,7%). Con respecto a la opinión sobre el uso de la ecografía en patologías específicas, se consideró con importancia y mucha importancia en artritis reumatoide (77,7%) y artropatías por cristales (72,7%), que fueron las más altas, así como para la realizaron de procedimientos (87%). Para la toma de decisiones en estudio de patología inflamatoria, el 60,4% consideraría realizar ecografía, comparado con 28,8% que se inclina por la resonancia. En relación con las limitaciones para la implementación, la falta de entrenamiento en el país (25,6%), seguida de la carencia de recursos para la consecución del equipo (17,9%) y el desconocimiento y la falta de interés por parte de los entes de salud (17,1%) fueron las más reconocidas.La ecografía musculoesquelética solamente es practicada por una minoría de los reumatólogos que ejercen en Colombia, a pesar de que la mayoría la considera importante. Su importancia radica en su uso para tratar a los pacientes con artritis reumatoide, artropatías por cristales y por artropatía psoriásica, así como para la realización de procedimientos. Más de la mitad de los reumatólogos han recibido algún tipo de formación en ecografía, la mayoría de las veces educación de muy pocas horas o sin entrenamiento practico o no formal, lo cual constituye el principal problema para su implementación.

There is still growing interest in graphene interactions with proteins, both for its possible biological applications and due to concerns over detrimental effects at the cellular level. As with any process involving proteins, an understanding of amino acid composition is desirable. In this work, we systematically studied the adsorption process of amino acids onto pristine graphene via rigorous free-energy calculations. We characterized the free energy, potential energy, and entropy of the adsorption of all proteinogenic amino acids. The energetic components were further separated into pair interaction contributions. A linear correlation was found between the free energy and the solvent accessible surface area change during adsorption (Delta SASA(ads)) over pristine graphene and uncharged amino acids. Free energies over pristine graphene were compared with adsorption onto graphene oxide, finding an almost complete loss of the favorability of amino acid adsorption onto graphene. Finally, the correlation with Delta SASA(ads) was used to successfully predict the free energy of adsorption of several penta-l-peptides in different structural states and sequences. Due to the relative ease of calculating the Delta SASA(ads) compared to free-energy calculations, it could prove to be a cost-effective predictor of the free energy of adsorption for proteins onto nonpolar surfaces.

BACKGROUND Neurofibromatosis 1 is a neurocutaneous disorder with multisystemic manifestations. When patients are lacking overt cutaneous manifestations, diagnosis may be delayed and may complicate diagnosis and management of atypical presentations of this disease. It is thus important to strive to obtain relevant and/or complete history to arrive at the appropriate diagnosis. Furthermore, maintaining an index of suspicion in cases of vague abdominal pain may guide the clinician in establishing the correct diagnosis of mesenteric plexiform neurofibroma in the setting of known/presumed neurofibromatosis 1 patients presenting with acute and/or chronic vague abdominal symptoms. CASE REPORT This is a case of a teenage boy who presented with acute, vague abdominal pain over a period of 2 weeks. Laboratory tests and physical exam findings in primary and secondary care settings were unremarkable, and thus the patient was discharged home only to continue with abdominal pain, thus seeking additional medical care. After admission to our facility and exhaustive history taking, physical examination, and imaging, a prospective diagnosis of neurofibromatosis with mesenteric neurofibroma was made. Upon surgical exploration, a mesenteric mass with corresponding volvulized, ischemic small bowel was removed. Histopathology confirmed a plexiform neurofibroma. The patient recovered adequately and was discharged home without complications. CONCLUSIONS This case highlights the importance of exhaustive history taking to obtain an accurate diagnosis as well as the importance of a high index of clinical suspicion for mesenteric neurofibromatosis in patients with presumed or known neurofibromatosis and presenting with vague abdominal symptoms.

La insuficiencia cardiaca aguda constituye la primera causa de hospitalización en las personas ancianas y es el principal factor determinante del enorme gasto de asistencia sanitaria asociado a la insuficiencia cardiaca. A pesar de los avances terapéuticos realizados, la insuficiencia cardiaca aguda tiene un mal pronóstico, con una mortalidad hospitalaria que oscila entre el 4 y el 7%, una mortalidad a los 60 a 90 días de entre el 7 y el 11% y una tasa de rehospitalizaciones a los 60 a 90 días que va del 25 al 30%. Hay varios factores, entre los que se encuentran los trastornos cardiovasculares y no cardiovasculares, así como factores relacionados con el paciente y factores iatrogénicos, que pueden desencadenar una progresión rápida o un agravamiento de los signos y síntomas de insuficiencia cardiaca, lo que conduce a un episodio de insuficiencia cardiaca aguda que suele requerir el ingreso hospitalario del paciente. La prevención primaria de la insuficiencia cardiaca aguda se centra principalmente en la prevención, el diagnóstico precoz y el tratamiento de los factores de riesgo cardiovascular y la cardiopatía, incluida la enfermedad coronaria, mientras que la prevención secundaria para evitar nuevos episodios de descompensación requiere la optimización del tratamiento de la insuficiencia cardiaca, la educación sanitaria del paciente y el desarrollo de una transición y un plan de seguimiento efectivos.Acute heart failure represents the first cause of hospitalization in elderly persons and is the main determinant of the huge healthcare expenditure related to heart failure. Despite therapeutic advances, the prognosis of acute heart failure is poor, with in-hospital mortality ranging from 4% to 7%, 60- to 90-day mortality ranging from 7% to 11%, and 60- to 90-day rehospitalization from 25% to 30%. Several factors including cardiovascular and noncardiovascular conditions as well as patient-related and iatrogenic factors may precipitate the rapid development or deterioration of signs and symptoms of heart failure, thus leading to an acute heart failure episode that usually requires patient hospitalization. The primary prevention of acute heart failure mainly concerns the prevention, early diagnosis, and treatment of cardiovascular risk factors and heart disease, including coronary artery disease, while the secondary prevention of a new episode of decompensation requires the optimization of heart failure therapy, patient education, and the development of an effective transition and follow-up plan.Full English text available from: www.revespcardiol.org/en

The Rad, Rem, Rem2, and Gem/Kir (RGK) sub-family of small GTP-binding proteins are crucial in regulating high voltage-activated (HVA) calcium channels. RGK proteins inhibit calcium current by either promoting endocytosis or reducing channel activity. They all can associate directly with Ca2+ channel β subunit (CaVβ), and the binding between CaVα1/CaVβ appears essential for the endocytic promotion of CaV1.X, CaV2.1, and CaV2.2 channels. In this study, we investigated the inhibition of CaV2.3 channels by RGK proteins in the absence of CaVβ. To this end, Xenopus laevis oocytes expressing CaV2.3 channels devoid of auxiliary subunit were injected with purified Gem and Rem and found that only Gem had an effect. Ca currents and charge movements were reduced by injection of Gem, pointing to a reduction in the number of channels in the plasma membrane. Since this reduction was ablated by co-expression of the dominant-negative mutant of dynamin K44A, enhanced endocytosis appears to mediate this reduction in the number of channels. Thus, Gem inhibition of CaV2.3 channels would be the only example of a CaVβ independent promotion of dynamin-dependent endocytosis.

Aquaporins (AQPs) are small transmembrane tetrameric proteins that facilitate water, solute and gas exchange. Their presence has been extensively reported in the biological membranes of almost all living organisms. Although their discovery is much more recent than ion transport systems, different biophysical approaches have contributed to confirm that permeation through each monomer is consistent with closed and open states, introducing the term gating mechanism into the field. The study of AQPs in their native membrane or overexpressed in heterologous systems have experimentally demonstrated that water membrane permeability can be reversibly modified in response to specific modulators. For some regulation mechanisms, such as pH changes, evidence for gating is also supported by high-resolution structures of the water channel in different configurations as well as molecular dynamics simulation. Both experimental and simulation approaches sustain that the rearrangement of conserved residues contributes to occlude the cavity of the channel restricting water permeation. Interestingly, specific charged and conserved residues are present in the environment of the pore and, thus, the tetrameric structure can be subjected to alter the positions of these charges to sustain gating. Thus, is it possible to explore whether the displacement of these charges (gating current) leads to conformational changes? To our knowledge, this question has not yet been addressed at all. In this review, we intend to analyze the suitability of this proposal for the first time.

Myeloid-derived suppressor cells (MDSC) are a heterogeneous cell population with high immunosuppressive activity that proliferates in infections, inflammation, and tumor microenvironments. In tumors, MDSC exert immunosuppression mainly by producing reactive oxygen species (ROS), a process triggered by the NADPH oxidase 2 (NOX2) activity. NOX2 is functionally coupled with the H(v)1 proton channel in certain immune cells to support sustained free-radical production. However, a functional expression of the H(v)1 channel in MDSC has not yet been reported. Here, we demonstrate that mouse MDSC express functional H(v)1 proton channel by immunofluorescence microscopy, flow cytometry, and Western blot, besides performing a biophysical characterization of its macroscopic currents via patch-clamp technique. Our results show that the immunosuppression by MDSC is conditional to their ability to decrease the proton concentration elevated by the NOX2 activity, rendering H(v)1 a potential drug target for cancer treatment.

The dissipation of acute acid loads by the voltage-gated proton channel (Hv1) relies on regulating the channel's open probability by the voltage and the ΔpH across the membrane (ΔpH = pHex - pHin). Using monomeric Ciona-Hv1, we asked whether ΔpH-dependent gating is produced during the voltage sensor activation or permeation pathway opening. A leftward shift of the conductance-voltage (G-V) curve was produced at higher ΔpH values in the monomeric channel. Next, we measured the voltage sensor pH dependence in the absence of a functional permeation pathway by recording gating currents in the monomeric nonconducting D160N mutant. Increasing the ΔpH leftward shifted the gating charge-voltage (Q-V) curve, demonstrating that the ΔpH-dependent gating in Hv1 arises by modulating its voltage sensor. We fitted our data to a model that explicitly supposes the Hv1 voltage sensor free energy is a function of both the proton chemical and the electrical potential. The parameters obtained showed that around 60% of the free energy stored in the ΔpH is coupled to the Hv1 voltage sensor activation. Our results suggest that the molecular mechanism underlying the Hv1 ΔpH dependence is produced by protons, which alter the free-energy landscape around the voltage sensor domain. We propose that this alteration is produced by accessibility changes of the protons in the Hv1 voltage sensor during activation.

Arachidonic acid (AA) is a fatty acid involved in the modulation of several ion channels. Previously, we reported that AA activates the high conductance Ca2+- and voltage-dependent K+ channel (BK) in vascular smooth muscle depending on the expression of the auxiliary β1 subunit. Here, using the patch-clamp technique on BK channel co-expressed with β1 subunit in a heterologous cell expression system, we analyzed whether AA modifies the three functional modules involved in the channel gating: the voltage sensor domain (VSD), the pore domain (PD), and the intracellular calcium sensor domain (CSD). We present evidence that AA activates BK channel in a direct way, inducing VSD stabilization on its active configuration observed as a significant left shift in the Q-V curve obtained from gating currents recordings. Moreover, AA facilitates the channel opening transitions when VSD are at rest, and the CSD are unoccupied. Furthermore, the activation was independent of the intracellular Ca2+ concentration and reduced when the BK channel was co-expressed with the Y74A mutant of the β1 subunit. These results allow us to present new insigths in the mechanism by which AA modulates BK channels co-expressed with its auxiliary β1 subunit.