The complete amino acid sequence of the foliitropin β-subunit of the bullfrog, rana catesbeiana

Abstract The amino acid sequence of the bullfrog, Rana catesbeiana , follitropin β-subunit has been determined by sequencing the intact protein (residues 1–39) and peptides originated by lysyl endopeptidase and pepsin. Twelve cysteine residues and two sugar chain binding sites at Asn-5 and Asn-22 are positional identities with bullfrog and mammalian β-subunits. The bullfrog FSH β-subunit is composed of 107 amino acid residues with a molecular mass of 11,782 Da, including the six cystine bridges and excepting the sugar chain. The bullfrog FSH β-subunit has approximately 60% sequence identity with that of mammals and 40% with the fish gonadotropin β-subunit. Conserved sequences among mammals (residue numbers 33–55 and 66–71) extensively differed from those of the bullfrog.