TGF-BETA RECEPTORS - STRUCTURE AND FUNCTION

The transforming growth factor beta (TGF-beta) superfamily of dimeric polypeptide growth factors regulate cell growth and differentiation an d play important roles in embryonic development and the immune respons e. The molecular cloning of three types of high affinity cell-surface receptors (type I, type II and type III) for these growth factors prov ide insights into their poorly understood mechanisms of action. Here w e focus on the structure of these receptors and on the complex interac tions which occur between different receptors that are necessary for l igand-induced signal transduction. The type I and type II receptors ar e both related transmembrane serine/threonine kinase receptors which m ay hetero-oligomerize to transduce proper signals. The type III recept or modulates the binding of ligands to the signaling complex of type I and type II receptors. These findings suggest that serine/threonine p hosphorylation and heteromeric receptor interactions are important ele ments of TGF-beta induced signaling.