 The Type I receptor phosphorylates an R-SMAD a transcriptional regulator.Unlike the TGFβ type II receptor, which has a high affinity for TGF-β1, BMPR2 does not have a high affinity for BMP-2, BMP-7 and BMP-4, unless it is co-expressed with a type I BMP receptor.On ligand binding, forms a receptor complex consisting of two type II and two type I transmembrane
serine/threonine kinases.