The 11beta hydroxysteroid dehydrogenase 2 exists as an inactive dimer.
The 11beta-hydroxysteroid dehydrogenase types 1 and 2 enzymes (11beta-HSD1 and 11beta-HSD2), modulate glucocorticoid occupation of the mineralocorticoid and glucocorticoid receptors by interconverting corticosterone and cortisol to the inactive metabolites 11-dehydrocorticosterone and cortisone within the target cells. The NAD(+)-dependent 11-HSD 2 in the kidney inactivates corticosterone and cortisol, allowing aldosterone, which is not metabolized, access to the receptor. Studies of the kinetics of 11-HSD 2 activity in the rat kidney have produced inconsistent results. Western blots done in the absence of the reducing agent beta-mercaptoethanol showed two bands with approximate MW of 40 and 80 kDa. When beta-mercaptoethanol was used, only the 40 kDa was detected, indicating that under non-denaturing conditions a significant proportion of the 11beta-HSD 2 exists as a dimer. NAD(+)-dependent conversion of 3H-corticosterone by 20 microg of microsomal protein increased approximately 10 fold with the addition of 5 mM DTT concentration. NADP(+)-dependent activity with 20 microg of microsomal protein was very low and did not change significantly when using DTT. In the presence of DTT, the predominant 11-HSD activity in the rat kidney is NAD(+)-dependent with a K(m) of 15.1 nM, similar to that of the cloned and expressed enzyme. These data suggest that dimerization and subsequent enzyme inactivation occur when protocols promoting oxidation of this protein are used.
Gomez-Sanchez
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EP
Endocrine Section and Research Service, G.V. (Sonny) Montgomery VA Medical Center, 1500 E Woodrow Wilson Dr (151), Jackson, MS 39216, USA. elise.gomezsanchez@med.va.gov
Ganjam
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Chen
Y J
YJ
Liu
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Clark
S A
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Gomez-Sanchez
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CE
D043209:11-beta-Hydroxysteroid Dehydrogenase Type 2; D000818:Animals; D015153:Blotting, Western / Q000379:methods; D019281:Dimerization; D004229:Dithiothreitol / Q000494:pharmacology; D004789:Enzyme Activation / Q000502:physiology; D006913:Hydroxysteroid Dehydrogenases / Q000187:drug effects / Q000378:metabolism*; D007668:Kidney / Q000166:cytology / Q000201:enzymology*; D007700:Kinetics; D008623:Mercaptoethanol / Q000494:pharmacology; D008861:Microsomes / Q000201:enzymology*; D011489:Protein Denaturation / Q000502:physiology; D051381:Rats; D011994:Recombinant Proteins / Q000187:drug effects / Q000378:metabolism
D011994:Recombinant Proteins; D008623:Mercaptoethanol; D006913:Hydroxysteroid Dehydrogenases; D043209:11-beta-Hydroxysteroid Dehydrogenase Type 2; D004229:Dithiothreitol