11β-hydroxysteroid dehydrogenase type 1 11β-hydroxysteroid dehydrogenase type 2
Chromosomal location 1q32.2 16q22
Gene and size HSD11B1 30kb, 6 exons HSD11B2 6.2kb, 5 exons
Protein size 292 amino acids, 34kDa 405 amino acids, 444kDa
Enzyme reactions Bi-directional: In vivo: oxoreductase In vitro: dehydrogenase Dehydrogenase
Action Converts inactive GC into active GC Converts active GC into inactive GC
Co-factor(s) Oxoreductase: NADPH Dehydrogenase: NADP+ NAD+
Distribution Mainly expressed in the liver, lungs, pituitary, brains and adipose tissues Mainly expressed in the kidney, colon,salivary gland and placenta
Substrate affinity Low affinity (Km in μM) Corticosterone 1.8μM Cortisol 17μM 11-dehydrocorticosterone ~0.12μ High affinity (Km in μM) Corticosterone 5nM Cortisol 50μM 11-dehydrocorticosterone negligible
Function (s) Regulation of intracellular active GC level Protection of mineralocorticoid binding of active GC receptors from
Table 1: Comparisons between 11β-hydroxysteroid dehydrogenase type 1 and 2 (NAD-nicotinamide adenine dinucleotide; NADPH- nicotinamide adenine dinucleotide phosphate; GC- glucocorticoids) [5,105].