A cellular mediator for the hypoglycemic action of a human growth hormone fragment (hGH 4-15).

Evidence is presented that the hypoglycemic action of the human growth hormone fragment, Ile-Pro-Leu-Ser-Arg-Leu-Phe-Asp-Asn-Ala (hGH 4-15) is due to the interaction of hGH 4-15 with plasma membrane resulting in a time- and temperature-dependent release of a cellular mediator which acts to increase insulin binding and hexose transport with consequent potentiation of insulin action. The findings suggest that the hGH 4-15 mediator is a low molecular weight (500-2000 daltons) peptide or has a small peptide moiety in its structure containing an aromatic residue but no arginine or lysine.