Phosphoglucomutase: its role in the response of pancreatic islets to glucose epimers and anomers.
Rat pancreatic islets display phosphoglucomutase activity. The velocity of glucose-1-phosphate conversion to glucose-6-phosphate is increased in a dose-related fashion by glucose-1,6-bisphosphate. The islet homogenate, like purified muscle phosphoglucomutase, also catalyzes the synthesis of glucose-1,6-bisphosphate from glucose-6-phosphate and fructose-1,6-bisphosphate. The rate of the latter reaction is about 10,000 times lower than that of glucose-1-phosphate conversion to glucose-6-phosphate in the presence of glucose-1,6-bisphosphate. D-glucose and D-mannose, but not D-galactose nor D-fructose, markedly increase the islet content in glucose-1,6-bisphosphate. Such a content is twice higher in islets exposed for 5 minutes to alpha-D-glucose than in islets exposed to beta-D-glucose. The process of glucose-1,6-bisphosphate synthesis, as catalyzed by the alpha-stereospecific phosphoglucomutase, may play a role in the metabolic and, hence, secretory responses of the islets to glucose epimers and anomers.
D000818:Animals; D005632:Fructose / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology*; D019298:Glucose-6-Phosphate / Q000031:analogs & derivatives*; D005958:Glucosephosphates / Q000378:metabolism; D007515:Islets of Langerhans / Q000187:drug effects* / Q000201:enzymology; D007536:Isomerism; D008358:Mannose / Q000494:pharmacology; D010733:Phosphoglucomutase / Q000378:metabolism*; D051381:Rats; D013997:Time Factors
D005958:Glucosephosphates; D005632:Fructose; D019298:Glucose-6-Phosphate; C016473:glucose-1,6-bisphosphate; D010733:Phosphoglucomutase; D005947:Glucose; D008358:Mannose