ActRII

TGF-beta family members transduce signals through a mechanism that includes a multistep process in which the TGF-beta family member binds a type II serine/threonine kinase receptor expressed on the cell surface, the type II receptor forms a heteromeric complex with a cognate type I receptor and activates the type I receptor through phosphorylation, the activated type-I receptor phosphorylates and activates Smad proteins that transduce the signal from the cytoplasm to the nucleus, and nuclear Smad oligomers bind to DNA and associate with transcription factors to regulate the expression of target genes.