HUMAN FOLLICLE STIMULATING HORMONE (hFSH): FIRST PROPOSAL FOR THE AMINO ACID SEQUENCE OF THE α-SUBUNIT (hFSHα) AND FIRST DEMONSTRATION OF ITS IDENTITY WITH THE α-SUBUNIT OF HUMAN LUTEINIZING HORMONE (hLHα)

Amino acid composition of hFSHα was similar to hFSHβ (except for methionines and isoleucines) and to hLHα and hTSHα. hFSHβ composition resembled hTSHβ more than hLHβ. The amino acid sequence of the α subunit of hFSH has been deduced from the sequences of tryptic and thermoiytic peptides of the reduced and carboxymethylated subunit. hFSHα has 89 amino acid residues, with a single isoleucine at position 22, and 2 carbohydrate moieties at 49 and 75. The sequence of hFSHα is identical to hLHα, as determined in our laboratory. The amino acid sequence of hFSHα is virtually identical to that of hCGα (21,22), except for 3 extra residues at the NH2-terminus of hCGα hFSHα possesses 29 positional differences from ovine LHα, including a deletion of 7 residues present at the NH2-terminus of ovine LHα.