The thymus gland produces several hormones or hormone-like substances which are derived from a polypeptide precursor containing (in the rat) 113 amino acids and known as prothymosin-alpha. A peptide containing 28 amino acid residues, named thymosin-alpha-1, was originally isolated from calf thymosin fraction 5 and shown to restore various aspects of immune function in several in vitro and invivo test systems. Thymosin-alpha-1 was subsequently isolated from a similar fraction from human thymosin and reported to have the same amino acid sequence as bovine thymosin-alpha-1. In 2003, Jiang et al. identified a pathway that regulates mitochondria-initiated caspase activity. In this pathway, putative human HLA class II-associated protein (PHAP) promoted caspase-9 activation after apoptosome formation, whereas prothymosin-alpha-1 negatively regulated caspase-9 activation by inhibiting apoptosome formation.
gene sequence 28; N-terminally processed; Prothymosin alpha; prothymosin alpha protein; Prothymosin alpha, N-terminally processed; PTMA; Thymosin alpha-1; TMSA