Thymosin al: Isolation and sequence analysis of an immunologically

The amino acid sequence of a biologically active polypeptide isolated from calf thymus, termed thymosin a1, has been determined. Thymosin ca1 is a heat stable, highly acidic molecule composed of 28 amino acid residues. This peptide is one of several present in thymosin fraction 5 that may participate in the regulation, differentiation, and function of thymus-dependent lymphocytes (T cells). A nomenclature for the family of polypeptides present in thymosin fraction 5 is suggested.