Catalytic domain of the Serine/Threonine Kinases, Bone Morphogenetic Protein and Anti-Muellerian Hormone Type II Receptors
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. BMPR2 and AMHR2 belong to a group of receptors for the TGFbeta family of secreted signaling molecules that includes TGFbeta, BMPs, activins, growth and differentiation factors (GDFs), and AMH, among others. These receptors contain an extracellular domain that binds ligands, a single transmembrane region, and a cytoplasmic catalytic kinase domain. Type II receptors are high-affinity receptors which bind ligands, autophosphorylate, as well as trans-phosphorylate and activate low-affinity type I receptors. BMPR2 and AMHR2 act primarily as a receptor for BMPs and AMH, respectively. BMPs induce bone and cartilage formation, as well as regulate tooth, kidney, skin, hair, haematopoietic, and neuronal development. Mutations in BMPR2A is associated with familial pulmonary arterial hypertension. AMH is mainly responsible for the regression of Mullerian ducts during male sex differentiation. It is expressed exclusively by somatic cells of the gonads. Mutations in either AMH or AMHR2 cause persistent Mullerian duct syndrome (PMDS), a rare form of male pseudohermaphroditism characterized by the presence of Mullerian derivatives (ovary and tubes) in otherwise normally masculine males. The BMPR2/AMHR2 subfamily is part of a larger superfamily that includes the catalytic domains of other STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase.