A protein complex acting as ligand of the transforming growth factor beta receptor complex, typically a homodimer of any of the TFGbeta isoforms. The precursor of TGFbeta proteins is cleaved into mature TGFbeta and the latency-associated peptide (LAP), which remains non-covalently linked to mature TGFbeta rendering it inactive. TGFbeta is activated by dimerization and dissociation of the LAP.
TGFbeta dimer