title: The regulatory protein of glucokinase binds to the hepatocyte matrix, but, unlike glucokinase, does not translocate during substrate stimulation.
abstract: The kinetic properties of hepatic glucokinase (hexokinase IV) are modulated by binding to a regulatory protein. This study shows that, in hepatocytes incubated with 5 mM glucose as sole carbohydrate substrate, both glucokinase and its regulatory protein bind to the cell matrix by a Mg(2+)-dependent mechanism. After incubation with an elevated [glucose] or with fructose, glucokinase, but not its regulatory protein, translocates from the Mg(2+)-dependent binding site. It is suggested that the regulatory protein acts as a receptor for anchoring glucokinase to the hepatocyte matrix and inhibiting its activity in metabolically quiescent conditions.
authors.affiliation: Department of Medicine, University of Newcastle upon Tyne, U.K.
authors.forename: L
authors.initials: L
authors.lastname: Agius
authors.forename: M
authors.initials: M
authors.lastname: Peak
authors.forename: E
authors.initials: E
authors.lastname: Van Schaftingen
mesh_terms: D000818:Animals; D001692:Biological Transport; D002352:Carrier Proteins; D002478:Cells, Cultured; D005941:Glucokinase / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008297:Male; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013379:Substrate Specificity
chemical_list: D002352:Carrier Proteins; C499484:Gckr protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; C080906:glucokinase regulatory protein; D005941:Glucokinase