Evolution of the genes for the β subunits of human chorionic gonadotropin and luteinizing hormone

Abstract

Nucleotide sequence comparisons of the single gene for the human luteinizing hormone gene β subunit with two of the seven genes for the human chorionic gonadotropin β subunit suggest that the β human chorionic gonadotropin genes have evolved from an ancestral β luteinizing hormone gene by a series of selected changes with very little neutral drift. Moreover, the 24 amino acid carboxy-terminal extension of the human chorionic gonadotropin β subunit appears to have arisen by a single base deletion that incorporated the 3′-untranslated region of the ancestral β luteinizing hormone gene into the coding region.