title: Cooperativity between 11beta-hydroxysteroid dehydrogenase type 1 and hexose-6-phosphate dehydrogenase in the lumen of the endoplasmic reticulum.
abstract: The functional coupling of 11beta-hydroxysteroid dehydrogenase type 1 and hexose-6-phosphate dehydrogenase was investigated in rat liver microsomal vesicles. The activity of both enzymes was latent in intact vesicles, indicating the intraluminal localization of their active sites. Glucose-6-phosphate, a substrate for hexose-6-phosphate dehydrogenase, stimulated the cortisone reductase activity of 11beta-hydroxysteroid dehydrogenase type 1. Inhibition of glucose-6-phosphate uptake by S3483, a specific inhibitor of the microsomal glucose-6-phosphate transporter, decreased this effect. Similarly, cortisone increased the intravesicular accumulation of radioactivity upon the addition of radiolabeled glucose-6-phosphate, indicating the stimulation of hexose-6-phosphate dehydrogenase activity. A correlation was shown between glucose-6-phosphate-dependent cortisone reduction and cortisone-dependent glucose-6-phosphate oxidation. The results demonstrate a close cooperation of the enzymes based on co-localization and the mutual generation of cofactors for each other.
authors.affiliation: Endoplasmic Reticulum Research Group of the Hungarian Academy of Sciences and Semmelweis University, Budapest.
authors.forename: Gábor
authors.initials: G
authors.lastname: Bánhegyi
authors.forename: Angelo
authors.initials: A
authors.lastname: Benedetti
authors.forename: Rosella
authors.initials: R
authors.lastname: Fulceri
authors.forename: Silvia
authors.initials: S
authors.lastname: Senesi
mesh_terms: D043205:11-beta-Hydroxysteroid Dehydrogenase Type 1 / Q000378:metabolism*; D000818:Animals; D002237:Carbohydrate Dehydrogenases / Q000378:metabolism*; D003348:Cortisone / Q000378:metabolism / Q000494:pharmacology; D003349:Cortisone Reductase / Q000378:metabolism; D003509:Cyclohexanecarboxylic Acids / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005952:Glucose-6-Phosphatase / Q000037:antagonists & inhibitors; D019298:Glucose-6-Phosphate / Q000378:metabolism / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology; D010084:Oxidation-Reduction; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D003509:Cyclohexanecarboxylic Acids; D004791:Enzyme Inhibitors; C113180:S 3483; D019298:Glucose-6-Phosphate; D002237:Carbohydrate Dehydrogenases; C020552:galactose-6-phosphate dehydrogenase; D043205:11-beta-Hydroxysteroid Dehydrogenase Type 1; D003349:Cortisone Reductase; D005952:Glucose-6-Phosphatase; D003348:Cortisone