The complete amino acid sequences of α subunits of chum salmon gonadotropins

The complete amino acid sequences of α subunits of chum salmon ( Oncorhynchus keta) gonadotropins (GTHs), GTH I and GTH II, were determined. Subunits were separated by reversed-phase high-performance liquid chromatography. Two α subunits, I α1 and I α2, were obtained from GTH I, whereas only one α subunit was obtained from GTH II. Sequence analysis revealed that GTH I α2 is identical to GTH II α, but distinct from GTH I α1. The I α1 and II α consist of 95 and 92 amino acid residues, respectively. GTH I α1 has 72% sequence identity with GTH I α2. The two α subunits show approximately 65% sequence identity with bovine α subunit. This is the first finding of two chemically distinct α subunits from one species.