The human growth hormone gene family: nucleotide sequences show recent divergence and predict a new polypeptide hormone.

The nucleotide sequences of three nonallelic human genomic DNA fragments which each contain one member of the growth hormone gene family are presented. These genes code for the known polypeptide hormones, growth hormone (hGH), chorionic somatomammotropin (hCS), and a yet unknown protein which differs from hGH in 13 positions. Each gene is structured into five exons, the four introns occurring at identical positions. Reflecting recent gene divergence, 90-95% sequence homology is seen in exons, introns, 5', and immediate 3' nontranscribed regions. The regions downstream of the polyadenylation sites in the genes for hGH and its variant, but not for hCS, contain members of an Alu family repeat sequence.