Cloning and Functional Expression of a Human Glucagon-like Peptide-1 Receptor

Abstract

A human glucagon-like 1 peptide receptor has been cloned from the gastric tumor cell line HGT-1. The cDNA clone encodes a protein of 463 amino acids and is a member of the superfamily of seven transmemhrane domain G protein coupled receptors. Transfection of the human GLP-1 receptor into COS-7 cells confers upon them high affinity binding for [ 125I] GLP-1(7-36) amide. In membranes prepared from COS-7 cells transfected with the human GLP-1 receptor, the binding of [ 125I] GLP-1 (7-36) amide is inhibited with the rank order of potency GLP-1 (7-36) amide > glucagon > secretin, characteristic of a GLP-1 receptor. The human GLP-1 receptor is functionally coupled to increases in intracellular cAMP in these cells: incubation of COS-7 cells expressing the human GLP-1 receptor with GLP-1 (7-36) amide gives rise to a 4-fold increase in cyclic AMP over basal levels, with an EC 50 of 25pM. Glucagon is also a full agonist but is 200-fold less potent than GLP-1 (7-36) amide in stimulating the human GLP-1 receptor.