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Cell biology of carbohydrate metabolism

Cell biology of carbohydrate metabolism: Regulation of metabolic pathways, glucose as a regulator of metabolism, a carbohydrate response element (ChoRE) consists of 2 E-box like elements separated by 5 nucleotides, metabolic control analysis,. | Cell biology of carbohydrate metabolism Glucose Glucose 6-phosphate Glycogen synthesis Glycogenolysis Glucokinase/ Hexokinase G6Pase Glycolysis Gluconeogenesis P Glycogen Lactate Pyruvate P Pentose phosphate pathway Ribose 5-phosphate Acetyl CoA TCA cycle Lipids Lipid synthesis ATP NADPH ATP Fructose Galactose Regulation of metabolic pathways The flow of intermediates through metabolic pathways is controlled by four mechanisms Substrate availability Allosteric activation or inhibition Covalent modification of enzymes Induction/repression of enzyme synthesis + the types of transporters and enzymes that exist in a certain cell type Fed state Fasted state glucose P GK glucose glucose-6-phosphate GLUT 2 Insulin receptor Insulin Lipids Pyruvate Hepatic glucose uptake and utilization Hepatic glucose production glucose P glucose glucose-6-phosphate GLUT 2 Receptor Glucagon Glycogen Gluconeogenesis G6Pase Liver cell - Hepatocyte Glycolysis Glycolysis Glycogen Rapidly contracting state Resting state glucose P Hexokinase glucose glucose-6-phosphate GLUT 4 glucose P glucose glucose-6-phosphate GLUT 4 Glycogen Skeletal muscle cell Glycogen Low ATP High AMP High Ca++ ATP Glycolysis Glycolysis High ATP Low AMP Low Ca++ ATP Fed state Fasted state glucose P Hexokinase glucose glucose-6-phosphate GLUT 4 glucose P glucose glucose-6-phosphate GLUT 4 Glycogen Skeletal muscle cell Glycogen ATP Glycolysis Glycolysis ATP Insulin receptor Insulin ? Fatty acids + ketone bodies ATP glucose P Hexokinase glucose glucose-6-phosphate GLUT 1 and 3 Brain cell ATP Glycolysis TCA cycle Glucose as a regulator of metabolism Concentration effects on enzymatic steps High Km of glucokinase determines rate of glucose catabolism and insulin secretion in pancreatic beta cells High Km of glucokinase allows liver cells to rapidly phosphorylate glucose at high concentrations Allosteric effector Glucose stimulates release of glucokinase from the glucokinase regulatory protein (GKRP) Glucose inhibits liver . | Cell biology of carbohydrate metabolism Glucose Glucose 6-phosphate Glycogen synthesis Glycogenolysis Glucokinase/ Hexokinase G6Pase Glycolysis Gluconeogenesis P Glycogen Lactate Pyruvate P Pentose phosphate pathway Ribose 5-phosphate Acetyl CoA TCA cycle Lipids Lipid synthesis ATP NADPH ATP Fructose Galactose Regulation of metabolic pathways The flow of intermediates through metabolic pathways is controlled by four mechanisms Substrate availability Allosteric activation or inhibition Covalent modification of enzymes Induction/repression of enzyme synthesis + the types of transporters and enzymes that exist in a certain cell type Fed state Fasted state glucose P GK glucose glucose-6-phosphate GLUT 2 Insulin receptor Insulin Lipids Pyruvate Hepatic glucose uptake and utilization Hepatic glucose production glucose P glucose glucose-6-phosphate GLUT 2 Receptor Glucagon Glycogen Gluconeogenesis G6Pase Liver cell - Hepatocyte Glycolysis Glycolysis Glycogen Rapidly contracting state Resting