Glucokinase

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Federal government websites often end in. The site is secure. Glucose transport is by facilitated diffusion and is not rate limiting. Once inside, glucose is phosphorylated to glucosephosphate by GCK in a reaction that is dependent on glucose throughout the physiological range of concentrations, is irreversible, and not product inhibited. High glycerol phosphate shuttle, pyruvate dehydrogenase, and pyruvate carboxylase activities, combined with low pentose-P shunt, lactate dehydrogenase, plasma membrane monocarboxylate transport, and glycogen synthase activities constrain glucosephosphate to being metabolized through glycolysis. Under these conditions, glycolysis produces mostly pyruvate and little lactate. Pyruvate either enters the citric acid cycle through pyruvate dehydrogenase or is carboxylated by pyruvate carboxylase.

Glucokinase

Official websites use. Share sensitive information only on official, secure websites. The GCK gene provides instructions for making a protein called glucokinase. This protein plays an important role in the breakdown of sugars particularly glucose in the body. Glucokinase is primarily found in the liver and in beta cells in the pancreas. Beta cells produce and release secrete the hormone insulin, which helps regulate blood glucose levels by controlling how much glucose is passed from the bloodstream into cells to be used as energy. Glucokinase acts as a sensor, recognizing when the level of glucose in the blood rises and helping stimulate the release of insulin from beta cells to control it. In the liver, glucokinase helps determine when excess glucose should be taken in and converted to glycogen, which is a major source of stored energy in the body. Mutations in the GCK gene cause maturity-onset diabetes of the young MODY , which is a group of conditions characterized by abnormally high blood glucose levels. This form of diabetes usually begins before age Affected individuals usually have mildly elevated blood glucose levels from birth, although they typically have no symptoms associated with the condition, and diabetes-related complications are extremely rare.

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Glucokinase EC 2. Glucokinase occurs in cells in the liver and pancreas of humans and most other vertebrates. In each of these organs it plays an important role in the regulation of carbohydrate metabolism by acting as a glucose sensor, triggering shifts in metabolism or cell function in response to rising or falling levels of glucose, such as occur after a meal or when fasting. Mutations of the gene for this enzyme can cause unusual forms of diabetes or hypoglycemia. Glucokinase GK is a hexokinase isozyme , related homologously to at least three other hexokinases.

Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. The secretion of glucagon by pancreatic alpha cells is regulated by a number of external and intrinsic factors. While the electrophysiological processes linking a lowering of glucose concentrations to an increased glucagon release are well characterized, the evidence for the identity and function of the glucose sensor is still incomplete. In the present study we aimed to address two unsolved problems: 1 do individual alpha cells have the intrinsic capability to regulate glucagon secretion by glucose, and 2 is glucokinase the alpha cell glucose sensor in this scenario. Single cell RT-PCR was used to confirm that glucokinase is the main glucose-phosphorylating enzyme expressed in rat pancreatic alpha cells.

Glucokinase

Federal government websites often end in. The site is secure. Type 2 diabetes mellitus is a metabolic disorder with complicated pathogenesis, and mono-target therapy often fails to effectively manage the levels of blood glucose. In recent years, the anti-diabetes target glucokinase GK has attracted the attention of researchers.

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Rorsman, P. Levels of F2,6P 2 play other amplifying roles in glycolysis in hepatocytes. Figure 1. Isolated primary rat alpha cells were prepared and transduced as described below. Whether this discrepancy is due to species differences or differences in culture conditions remains to be investigated. Cell Biol. Reprints and permissions. Glucagon secretion is regulated by a multitude of external and intrinsic pathways. The use of pHluorins for optical measurements of presynaptic activity. In order to carry out their role in monosaccaride metabolism, liver cells have a high capacity complement of glucokinase, fructokinase C, and galactokinase 1. Regulation of insulin secretion studies with pieces of rabbit pancreas incubated in vitro. The most recent overview of GCK mutation that were observed in patients claims mutations, of which are thought to cause the MODY diabetes and therefore reduce the functional efficiency of the glucokinase molecule.

Federal government websites often end in. The site is secure. Glucose metabolism in humans is tightly controlled by the activity of glucokinase GCK.

Fiji: an open-source platform for biological-image analysis. Interrelationship of islet metabolism, adenosine triphosphate content and insulin release. Matschinsky F. Small molecule glucokinase activators as glucose lowering agents: a new paradigm for diabetes therapy. Rorsman, P. Glucokinase is a monomeric protein of amino acids and a molecular weight of about 50 kD. Three lines of evidence support this contention. Displacement from this level, typically associated with altered insulin production or efficacy, gives rise to a wide range of pathologies. Glucokinase transcription becomes nearly undetectable in prolonged starvation, severe carbohydrate deprivation, or untreated insulin-deficient diabetes. Phosphoglycerate Aspartate kinase. In contrast to non-transgenic mice treated with streptozotocin, when mice with transgene were treated with streptozotocin their livers showed high levels of both GCK mRNA and activity. Health Conditions Related to Genetic Changes Maturity-onset diabetes of the young Mutations in the GCK gene cause maturity-onset diabetes of the young MODY , which is a group of conditions characterized by abnormally high blood glucose levels. National Center for Biotechnology Information, U. The metabolic actions of glucagon revisited.