OpEn-Tag: a customizable optogenetic toolbox to dissect subcellular signaling.

Subcellular localization of signal molecules is a hallmark in organizing the signal network. OpEn-Tag is a modular optogenetic endomembrane targeting toolbox that allows alteration of the localization and therefore the activity of signaling processes with the spatio-temporal resolution of optogenetics. OpEn-Tag is a two-component system employing 1) a variety of targeting peptides, fused to and thereby dictating the localization of mCherry-labeled cryptochrome 2 binding protein CIBN towards distinct endomembranes and 2) the cytosolic, fluorescence-labeled blue light photoreceptor cryptochrome 2 as customizable building block that can be fused to proteins of interest. The combination of OpEn-Tag with growth factor stimulation or the use of two membrane anchor sequences allows investigation of multilayered signal transduction processes as demonstrated here for the protein kinase AKT.