The objective of this proposal is to identify the regions of the insulin receptor molecule to which insulin binds and to identify their role in determining ligand specificity and in initiating signal transduction. Insulin resistance is commonly associated with glucose intolerance in humans, particularly with non-insulin dependent diabetes mellitus. Recently genetic defects of the insulin receptor have been shown to be responsible for certain syndromes of extreme insulin resistance. Thus understanding of the structure and function of the insulin binding site of the insulin receptor should provide further insights into the pathology of insulin resistance. Moreover knowledge obtained from this study could lead to the development of modified insulins with greater specificity for metabolic rather than mitogenic responses and with greater potency. Previous studied in this laboratory have identified an important role for phenylalanine 89 of the insulin receptor in insulin binding. This will serve as a starting point for the identification of more extensive regions of the receptor involved in insulin binding by site directed mutagenesis and the construction of chimeric molecules utilizing domains of the insulin and insulin-like Growth Factor I receptors.
The specific aims of the proposed research are: 1. To identify regions of the receptor involved in insulin binding 2. To utilize site directed mutagenesis to define the roles of individual amino acids in insulin binding 3. To evaluate the role of the hetero-tetrameric receptor structure in high affinity ligand binding 4. To determine the roles of individual amino acids within the insulin binding region in initiating biological responses to insulin 5. To determine the role of the insulin binding site in suppressing receptor autophosphorylation and biological activity

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
1R01DK042171-01
Application #
3243224
Study Section
Physiological Chemistry Study Section (PC)
Project Start
1990-02-01
Project End
1995-01-31
Budget Start
1990-02-01
Budget End
1991-01-31
Support Year
1
Fiscal Year
1990
Total Cost
Indirect Cost
Name
State University New York Stony Brook
Department
Type
Schools of Medicine
DUNS #
804878247
City
Stony Brook
State
NY
Country
United States
Zip Code
11794
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Mynarcik, D C; Williams, P F; Schaffer, L et al. (1997) Analog binding properties of insulin receptor mutants. Identification of amino acids interacting with the COOH terminus of the B-chain of the insulin molecule. J Biol Chem 272:2077-81
Conlon, J M; Secor, S M; Adrian, T E et al. (1997) Purification and characterization of islet hormones (insulin, glucagon, pancreatic, polypeptide and somatostatin) from the Burmese python, Python molurus. Regul Pept 71:191-8
Mynarcik, D C; Yu, G Q; Whittaker, J (1996) Alanine-scanning mutagenesis of a C-terminal ligand binding domain of the insulin receptor alpha subunit. J Biol Chem 271:2439-42
Conlon, J M; Cavanaugh, E S; Mynarcik, D C et al. (1996) Characterization of an insulin from the three-toed amphiuma (Amphibia: Urodela) with an N-terminally extended A-chain and high receptor-binding affinity. Biochem J 313 ( Pt 1):283-7
Williams, P F; Mynarcik, D C; Yu, G Q et al. (1995) Mapping of an NH2-terminal ligand binding site of the insulin receptor by alanine scanning mutagenesis. J Biol Chem 270:3012-6
Conlon, J M; Bondareva, V; Rusakov, Y et al. (1995) Characterization of insulin, glucagon, and somatostatin from the river lamprey, Lampetra fluviatilis. Gen Comp Endocrinol 100:96-105
Mynarcik, D C; Whittaker, J (1995) Insulin receptor transmembrane signaling: evidence for an intermolecular oligomerization mechanism of activation. J Recept Signal Transduct Res 15:887-904
Giorgino, F; Belfiore, A; Milazzo, G et al. (1991) Overexpression of insulin receptors in fibroblast and ovary cells induces a ligand-mediated transformed phenotype. Mol Endocrinol 5:452-9
Conlon, J M; Youson, J H; Whittaker, J (1991) Structure and receptor-binding activity of insulin from a holostean fish, the bowfin (Amia calva). Biochem J 276 ( Pt 1):261-4