Bone morphogenetic protein receptors are serine-threonine kinase receptors. Transforming growth factor beta family proteins bind to these receptors. There are four bone morphogenetic protein receptors:
Bone morphogenetic protein receptor, type 1: ACVR1 BMPR1A BMPR1B Bone morphogenetic protein receptor, type 2
Structure
Both type 1 and 2 bone morphogenetic protein receptors have a single transmembrane segment. Additionally, both types have a cysteine-rich extracellular domain and a cytoplasmic serine threonine kinase domain. Type 1 contains a glycine-serine-rich domain to be phosphorylated by type 2 kinase domain, initiating the signaling transduction pathway of the SMAD signaling cascade. The wrist epitope motif on BMP-2 has a high-affinity binding site for BMPR-IA. The knuckle epitope motif on BMP-2 has a low-affinity binding site for BMPR-II.