Abstract
The impact of hexose-6-phosphate dehydrogenase (H6PDH) on 11beta-hydroxysteroid dehydrogenase (11beta-HSD) type 1 activity was investigated upon coexpression in HEK-293 cells. Confocal microscopy analysis indicated colocalisation of both enzymes at the lumenal side of the endoplasmic reticulum (ER) membrane. Functional analysis in intact cells revealed fivefold stimulation of 11beta-HSD1 oxoreductase activity and sixfold decrease of dehydrogenase activity upon coexpression with H6PDH, without changing kinetic parameters in cell lysates. Thus, H6PDH directly determines the reaction direction of 11beta-HSD1 in intact cells as an oxoreductase without changing intrinsic catalytic properties of 11beta-HSD1 by regenerating NADPH in the ER-lumen.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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11-beta-Hydroxysteroid Dehydrogenases / genetics
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11-beta-Hydroxysteroid Dehydrogenases / metabolism*
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5' Untranslated Regions / genetics
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Adipocytes / enzymology
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Base Sequence
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Carbohydrate Dehydrogenases / genetics
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Carbohydrate Dehydrogenases / metabolism*
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Cell Line
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Cloning, Molecular
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Cortisone / metabolism
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Humans
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Hydrocortisone / metabolism
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Kidney
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Kinetics
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Oxidoreductases / genetics
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Oxidoreductases / metabolism
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Polymerase Chain Reaction
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RNA, Messenger / genetics
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Recombinant Proteins / metabolism
Substances
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5' Untranslated Regions
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RNA, Messenger
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Recombinant Proteins
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Oxidoreductases
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Carbohydrate Dehydrogenases
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galactose-6-phosphate dehydrogenase
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11-beta-Hydroxysteroid Dehydrogenases
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Cortisone
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Hydrocortisone