Avian thymic hormone (ATH) is a parvalbumin.

Amino acid sequence analysis of a protein from chicken thymus tissue which promotes immunological maturity in chicken bone marrow cells in culture has established sequences of a 45-residue fragment, a 24-residue fragment and a 9-residue and an 8-residue peptide. Independent comparison of the 45- and 24-residue fragments with known amino acid sequences by computer search has unequivocally identified avian thymic hormone as a parvalbumin. This is the first demonstration that a protein previously identified by a biological function is a parvalbumin.