Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
Coexpression of glucose transporters and glucokinase in Xenopus oocytes indicates that both glucose transport and phosphorylation determine glucose utilization.
Morita H
,
Yano Y
,
Niswender KD
,
May JM
,
Whitesell RR
,
Wu L
,
Printz RL
,
Granner DK
,
Magnuson MA
,
Powers AC
.
???displayArticle.abstract???
A Xenopus oocyte expression system was used to examine how glucose transporters (GLUT 2 and GLUT 3) and glucokinase (GK) activity affect glucose utilization. Uninjected oocytes and low rates of both glucose transport and phosphorylation; expression of GLUT 2 or GLUT 3 increased glucose phosphorylation approximately 20-fold by a low Km, endogenous hexokinase at glucose concentrations < or = 1 mM, but not at higher glucose concentrations. Coexpression of functional GK isoforms with GLUT 2 or 3 increased glucose utilization approximately an additional two- to threefold primarily at the physiologic glucose concentrations of 5-20 mM. The Km for glucose of both the hepatic and beta cell isoforms of GK, determined in situ, was approximately 5-10 mM when coexpressed with either GLUT 2 or GLUT 3. The increase in glucose utilization by coexpression of GLUT 3 and GK was dependent upon glucose phosphorylation since two missense GK mutations linked with maturity-onset diabetes, 182: Val-->Met and 228:Thr-->Met, did not increase glucose utilization despite accumulation of both a similar amount of immunoreactive GK protein and glucose inside the cell. Coexpression of a mutant GK and a normal GK isoform did not interfere with the function of the normal GK enzyme. Since the coexpression of GK and a glucose transporter in oocytes resembles conditions in the hepatocyte and pancreatic beta cell, these results indicate that increases in glucose utilization at glucose concentrations > 1 mM depend upon both a functional glucose transporter and GK.
Andreone,
The amino acid sequence of rat liver glucokinase deduced from cloned cDNA.
1989, Pubmed
Andreone,
The amino acid sequence of rat liver glucokinase deduced from cloned cDNA.
1989,
Pubmed
Byrne,
Insulin secretory abnormalities in subjects with hyperglycemia due to glucokinase mutations.
1994,
Pubmed
Fajans,
MODY: a model for the study of the molecular genetics of NIDDM.
1992,
Pubmed
Froguel,
Close linkage of glucokinase locus on chromosome 7p to early-onset non-insulin-dependent diabetes mellitus.
1992,
Pubmed
Garcia,
Amino acid substitutions at tryptophan 388 and tryptophan 412 of the HepG2 (Glut1) glucose transporter inhibit transport activity and targeting to the plasma membrane in Xenopus oocytes.
1992,
Pubmed
,
Xenbase
Gidh-Jain,
Glucokinase mutations associated with non-insulin-dependent (type 2) diabetes mellitus have decreased enzymatic activity: implications for structure/function relationships.
1993,
Pubmed
Gould,
Expression of human glucose transporters in Xenopus oocytes: kinetic characterization and substrate specificities of the erythrocyte, liver, and brain isoforms.
1991,
Pubmed
,
Xenbase
Hammerstedt,
The use of Dowex-1-borate to separate 3HOH from 2-3H-glucose.
1973,
Pubmed
Hattersley,
Linkage of type 2 diabetes to the glucokinase gene.
1992,
Pubmed
Jetton,
Heterogeneous expression of glucokinase among pancreatic beta cells.
1992,
Pubmed
Kahn,
Regulation of glucose-transporter gene expression in vitro and in vivo.
1990,
Pubmed
Katz,
The metabolism of glucose-2-T by adipose tissue.
1969,
Pubmed
Kunkel,
Efficient site-directed mutagenesis using uracil-containing DNA.
1991,
Pubmed
Liang,
Effects of alternate RNA splicing on glucokinase isoform activities in the pancreatic islet, liver, and pituitary.
1991,
Pubmed
Liang,
Concordant glucose induction of glucokinase, glucose usage, and glucose-stimulated insulin release in pancreatic islets maintained in organ culture.
1992,
Pubmed
Magnuson,
Rat glucokinase gene: structure and regulation by insulin.
1989,
Pubmed
Matschinsky,
Glucokinase as glucose sensor and metabolic signal generator in pancreatic beta-cells and hepatocytes.
1990,
Pubmed
Meglasson,
New perspectives on pancreatic islet glucokinase.
1984,
Pubmed
Meglasson,
Pancreatic islet glucose metabolism and regulation of insulin secretion.
1986,
Pubmed
Newgard,
Glucokinase and glucose transporter expression in liver and islets: implications for control of glucose homoeostasis.
1990,
Pubmed
Nishimura,
Kinetics of GLUT1 and GLUT4 glucose transporters expressed in Xenopus oocytes.
1993,
Pubmed
,
Xenbase
Permutt,
Glucokinase and NIDDM. A candidate gene that paid off.
1992,
Pubmed
Purich,
The hexokinases: kinetic, physical, and regulatory properties.
1973,
Pubmed
Quaade,
Analysis of the protein products encoded by variant glucokinase transcripts via expression in bacteria.
1991,
Pubmed
Stoffel,
Human glucokinase gene: isolation, characterization, and identification of two missense mutations linked to early-onset non-insulin-dependent (type 2) diabetes mellitus.
1992,
Pubmed
Tanizawa,
Human glucokinase gene: isolation, structural characterization, and identification of a microsatellite repeat polymorphism.
1992,
Pubmed
Thorens,
Facilitated glucose transporters in epithelial cells.
1993,
Pubmed
,
Xenbase
Trus,
Regulation of glucose metabolism in pancreatic islets.
1981,
Pubmed
Unger,
Diabetic hyperglycemia: link to impaired glucose transport in pancreatic beta cells.
1991,
Pubmed
Velho,
Primary pancreatic beta-cell secretory defect caused by mutations in glucokinase gene in kindreds of maturity onset diabetes of the young.
1992,
Pubmed
Vionnet,
Nonsense mutation in the glucokinase gene causes early-onset non-insulin-dependent diabetes mellitus.
1992,
Pubmed
Whitesell,
Coupling of glucose transport and phosphorylation in Xenopus oocytes and cultured cells: determination of the rate-limiting step.
1993,
Pubmed
,
Xenbase