A Novel Role for Glucose 6-Phosphatase in the Small Intestine in the Control of Glucose Homeostasis

Glucose 6-phosphatase (EC 3.1.3.9, Glc-6-Pase) 1 is a crucial enzyme in the control of glucose homeostasis. It catalyzes the last biochemical reaction of gluconeogenesis and glycogenolysis, i.e. the hydrolysis of glucose 6-phosphate (Glc-6-P) into glucose and P i . Glc-6-Pase is therefore unique in that it confers upon the tissues in which it is expressed the capacity to release glucose into the blood. It has long been recognized that the liver and the kidney possess this capacity because both tissues express high levels of Glc-6-Pase (1-4). Glc-6-Pase is a hydrophobic protein that is embedded within endoplasmic reticulum membrane (1-4). The reason for this localization is not clear.