Background information
Transforming growth factor beta 3 (TGF-β3) belongs to a family of pleiotropic homologous, disulfide-linked, homodimeric proteins (TGF-β1, TGF-β2, TGF-β3, TGF-β4, TGF-β5), which signal via the same receptor complex, and share similar biological functions. The TGF-β3 family is part of a bigger superfamily including activins, inhibins, growth and differentiation factors (GDFs) and bone morphogenetic proteins (BMPs), but is not related to TGF-α.
The members of the TGF-β family are expressed in platelets, leukocytes, endothelial cells, chondrocytes and keratinocytes. They are secreted and stored in a biologically inactive long form, establishing latent complexes at the cell surface and in the extracellular matrix. The immature form becomes active upon proteolytic cleavage, and forms active dimers linked by a disulfide-rich core consisting of the characteristic 'cysteine knot'. The members of the TGF-β family regulate cell proliferation, differentiation, migration, and play a key role in extracellular matrix formation, epithelial-mesenchymal transition, embryogenesis, tissue remodeling, and several immune functions. The specific physiological role of TGF-β3 is not completely known, but evidences show an involvement in cellular adhesion, extracellular matrix formation, lung and palate development, and epidermal and dermal cell migration during wound healing. The immature precursor of TGF-β3 is 412 amino acids long and it is cleaved to form a mature subunits of 112 amino acids. Human TGF-β3 is a recombinant homodimer corresponding to the fully mature form of TGF-β3 without LAP. The TGF-β family is evolutionarily conserved across the mammalians, and shows 98% sequence identity.
