Transforming growth factors TGFs

Transforming growth factors (TGFs) represent yet another family of polypeptide mitogens. The members of this family include TGF-a, as well as several species of TGF- S. 

TGF-a is initially synthesized as an integral membrane protein. Proteolytic cleavage releases the soluble growth faetor, which is a 50 amino acid polypeptide. This growth factor exhibits a high 

TGF-P was first described as a growth factor capable of inducing transformation of several fibroblast cell lines (hence the name, transforming growth factors). It is now recognized that 

The TGF- Ss exert their biological actions by binding to specific receptors, of which there are three types (I, II and III). All are transmembrane glycoproteins. All three TGF-)Ss bind to all three receptor types, although they bind with higher affinity to types I and II receptors (53 kDa and 65 kDa, respectively). The intracellular domains of the type I and II receptors display endogenous serine/threonine protein kinase activity. 

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Zhang XL, Topley N, Ito T, Phillips A Interleukin-6 regulation of transforming growth factor (TGF)-beta receptor compartmentalization and turnover enhances TGF-betal signaling. J Biol Chem 2005 280 12239-12245. 

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