Cooperativity between 11beta-hydroxysteroid dehydrogenase type 1 and hexose-6-phosphate dehydrogenase is based on a common pyridine nucleotide pool in the lumen of the endoplasmic reticulum

11 beta-Hydroxysteroid dehydrogenase type 1 (11 beta HSD1) is a NADP(H)-dependent oxidoreductase of the ER lumen, which may have an important role in the pathogenesis of metabolic syndrome. Here, the functional coupling of 11 beta-hydroxysteroid dehydrogenase type 1 and hexose-6-phosphate dehydrogenase (H6PDH) was investigated in rat liver microsomal vesicles. The results demonstrate the existence of a separate intraluminal pyridine nucleotide pool in the hepatic endoplasmic reticulum and a close cooperation between 11 beta PHSD1 and H6PDH based on their co-localization and the mutual generation of cofactors for each other. (c) 2005 Elsevier Ireland Ltd. All rights reserved.