[Transforming growth factor-beta and its receptors].

Transforming growth factor-beta (TGF-beta) is a family of multifunctional proteins that inhibit the growth of most cell types, and these proteins induce the deposition of extracellular matrix. TGF-beta inhibits the growth and migration of endothelial cells in vitro, but induces angiogenesis in vivo. TGF-beta belongs to a larger superfamily known as the TGF-beta superfamily, which includes activins and bone morphogenetic proteins. TGF-beta is produced as latent high molecular weight complexes from producer cells and is then activated by plasmin or thrombospondin. Latent TGF-beta binding protein (LTBP) is a component of the latent TGF-beta complex produced from platelets and many other cell types; LTBP plays an important role for the interaction of the latent TGF-beta complex with extracellular matrix components. TGF-beta binds several cell surface receptors, including type III receptor (betaglycan), endoglin, type II receptor and type I receptor. The type III receptor and endoglin are indirectly involved in the signal transduction. The Type II and type I receptors have intracellular serine/threonine kinase domains. They form a heteromeric complex after ligand binding and are most important for signal transduction; the type II receptor transactivates the type I receptor, which transduces various signals.