Activin Receptors

Synonyms

Activin receptor type 2; Activin receptor type I; Activin receptor-like kinase; ActRI; ActRII; ACVR1; ACVR2; ALK

Definition

Activin receptors are transmembrane serine threonine kinases that bind activins and subsequently trigger an intracellular signaling cascade. There are two types of activin receptors designated as type I and type II. Activins first bind type II receptors, whereupon type I receptors are recruited into the complex, which leads to the phosphorylation of intracellular signaling mediators called Smads. In a wider sense, however, the term activin receptor-like kinase (ALK) is also used for the structurally related type I receptors that transmit signals from other cytokines of the transforming growth factor beta (TGFβ) family including TGFβ itself, bone morphogenetic proteins (BMP), myostatin, growth and differentiation factors (GDF), and Müllerian inhibitory substance (MIS). Confusingly, the abbreviation ALK is also used for anaplastic lymphoma kinase– a...