Multiple type-beta transforming growth factors and their receptors.

Type beta transforming growth factors are a group of homologous structurally related polypeptides that act on a wide variety of cell types to alter their proliferative and phenotypic properties. TGF-beta s form a group within a larger family of polypeptides that control developmental processes in organisms from humans to Drosophila. We have found that at least three distinct forms of TGF-beta are present in mammalian tissues. We have identified a family of cell surface glycoproteins that bind TGF-beta s with high affinity and specificity. Examination of the interactions between individual forms of TGF-beta and the individual TGF-beta receptor species has illustrated a complex pattern of ligand-receptor associations. Occupancy of a particular receptor type by TGF-beta can be correlated to the dictation of specific effects on cell proliferation and cell differentiation.