Glucagon is a 29 amino acid pancreatic hormone that counteracts the blood glucose lowering action of insulin by stimulation of hepatic glycogenolysis and gluconeogenesis. Hormone activation of adenylate cyclase requires at least three membrane components; hormone receptor, catalytic subunit and GTP-regulatory component (Gs) that couples hormone binding to cyclase activation. Isolation and characterization of these components is essential for understanding the mechanism of the sequential events that begin with hormone binding and end with increase in cyclase activity. Although glucagon regulation of adenylate cyclase activity has been extensively studied, our knowledge about glucagon receptor itself lags behind the understanding of insulin or beta-adrenergic receptors. Recently we have identified glucagon receptor as a 62 kda glycoprotein that contains intrachain disulfide bonds and N-linked carbohydrate. To aid in studies of the glucagon receptor we prepared monoclonal antibodies (MAbs) that recognize the glucagon receptor. These antibodies were used to clone the cDNA encoding the glucagon receptor, from the expression library. In this proposal we outlined our planes for further characterization of the glucagon receptor and of its gene. The rat and human genomic sequences will be isolated by screening library with cDNA probe, and the glucagon receptor gene will be characterized with respect to intron/exon organization, regulatory features of the 5'end, and transcription initiation site. In the separate line of experiments we will study the postranslational modifications of the receptor such as phosphorylation and fatty acid acylation and the role these modification play in the ability of the receptor to activate adenylate cyclase. It is hoped that the results of the proposed experiments will contribute to our understanding of the mechanism of glucagon action.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
1R01DK043794-01
Application #
3245275
Study Section
Physiology Study Section (PHY)
Project Start
1991-05-20
Project End
1995-04-30
Budget Start
1991-05-20
Budget End
1992-04-30
Support Year
1
Fiscal Year
1991
Total Cost
Indirect Cost
Name
University of Minnesota Twin Cities
Department
Type
Schools of Arts and Sciences
DUNS #
168559177
City
Minneapolis
State
MN
Country
United States
Zip Code
55455