Properties of Human Growth Hormone Polypeptides: Purified from Pituitary Extracts and Synthesized in Monkey Kidney Cells and Bacteria

Abstract

Several forms of human GH (hGH) have been elucidated by extraction of human pituitary and recombinant DNA techniques. In the present study we have characterized five of these hGH polypeptides by gel filtration, RIA, and radioreceptor assays. These include extractable pituitary hGH and its naturally occurring 20K variant. Two hGH polypeptides were produced from naturally occurring human genes in simian kidney cells (SV-hGH 1 and 2) and another preparation was produced from a partially synthesized gene in bacteria (E. coli-hGH). As predicted from their known DNA sequences, naturally occurring pituitary hGH, SV-hGH 1, and E. coli-hGK migrated as a single peak on Sephadex G-100 column and had the same immunological and receptor-binding properties. By contrast, SV-hGH 2 (14 dispersed amino acid substitutions) and the 20K variant (amino acid residues 32–46 deleted from hGH) contained more higher molecular weight components and had diminished immunological and receptor-binding potency. SV-hGH 2 differed from the 20K variant by having even lower immunological potency and containing more of the higher molocular weight component. These variant forms of hGH may provide an explanation for the heterogeneity of both pituitary and plasma hGH.