Activin Receptors

Receptors for Activins are Membrane Protein Kinases belonging to the Family of Protein-Serine-Threonine Kinases, thus also named Activin receptor-like Kinases (ALK's). Activin receptors also bind Transforming Growth Factor beta. As those transmembrane receptors of the TGF-beta superFamily (Receptors, Transforming Growth Factor beta), ALK's consist of two different but related Protein Kinases, Type I and Type II. Activins initiate cellular Signal Transduction by first binding to the type II receptors (Activin Receptors, Type II ) which then recruit and phosphorylate the type I receptors (Activin Receptors, Type I ) with subsequent activation of the type I Kinase activity.