title: PTG, a protein phosphatase 1-binding protein with a role in glycogen metabolism.
abstract: Protein dephosphorylation by phosphatase PP1 plays a central role in mediating the effects of insulin on glucose and lipid metabolism. A PP1C-targeting protein expressed in 3T3-L1 adipocytes (called PTG, for protein targeting to glycogen) was cloned and characterized. PTG was expressed predominantly in insulin-sensitive tissues. In addition to binding and localizing PP1C to glycogen, PTG formed complexes with phosphorylase kinase, phosphorylase a, and glycogen synthase, the primary enzymes involved in the hormonal regulation of glycogen metabolism. Overexpression of PTG markedly increased basal and insulin-stimulated glycogen synthesis in Chinese hamster ovary cells overexpressing the insulin receptor, which do not express endogenous PTG. These results suggest that PTG is critical for glycogen metabolism, possibly functioning as a molecular scaffold.
authors.affiliation: Department of Physiology, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Printen
authors.forename: M J
authors.initials: MJ
authors.lastname: Brady
authors.forename: A R
authors.initials: AR
authors.lastname: Saltiel
mesh_terms: D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D006224:Cricetinae; D018076:DNA, Complementary / Q000235:genetics; D006003:Glycogen / Q000096:biosynthesis / Q000378:metabolism*; D006006:Glycogen Synthase / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D008969:Molecular Sequence Data; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010764:Phosphorylase Kinase / Q000378:metabolism; D010762:Phosphorylase a / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D054645:Protein Phosphatase 1; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013379:Substrate Specificity; D014162:Transfection
chemical_list: D002352:Carrier Proteins; D018076:DNA, Complementary; D007328:Insulin; D047908:Intracellular Signaling Peptides and Proteins; C104748:Ppp1r3c protein, mouse; D011993:Recombinant Fusion Proteins; D006003:Glycogen; D010762:Phosphorylase a; D006006:Glycogen Synthase; D010764:Phosphorylase Kinase; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1