Mutational analysis of the putative Anti-Müllerian Hormone (AMH) binding interface on its type II receptor, AMHR2.

Anti-Mullerian hormone (AMH) or Mullerian inhibiting substance is a unique member of the TGF-beta family responsible for development and differentiation of the reproductive system. AMH signals through its own dedicated type II receptor, anti-Mullerian hormone receptor type II (AMHR2), providing an exclusive ligand-receptor pair within the broader TGF-beta family. In this study, we used previous structural information to derive a model of AMH bound to AMHR2 to guide mutagenesis studies to identify receptor residues important for AMH signaling. Nonconserved mutations were introduced in AMHR2 and characterized in an AMH-responsive cell-based luciferase assay and native PAGE. Collectively, our results identified several residues important for AMH signaling within the putative ligand binding interface of AMHR2. Our results show that AMH engages AMHR2 at a similar interface to how activin and BMP class ligands bind the type II receptor, ACVR2B; however, there are significant molecular differences at the ligand interface of these 2 receptors, where ACVR2B is mostly hydrophobic and AMHR2 is predominately charged. Overall, this study shows that although the location of ligand binding on the receptor is similar to ACVR2A, ACVR2B, and BMPR2; AMHR2 uses unique ligand-receptor interactions to impart specificity for AMH.