The albumin I protein, a hormone-like peptide, stimulates kinase activity upon binding a membrane bound 43 kDa receptor. This domain represents the a chain.

1: A possible physiological function and the tertiary structure of a 4-kDa peptide in legumes. Yamazaki T, Takaoka M, Katoh E, Hanada K, Sakita M, Sakata K, Nishiuchi Y, Hirano H; Eur J Biochem 2003;270:1269-1276. PMID:12631285