Related Experiment Videos
Functional studies of 11 beta-hydroxysteroid dehydrogenase
P C White1, T Mune, A K Agarwal
1Division of Pediatric Endocrinology, Cornell University Medical College, New York, New York, USA.
Steroids
|January 1, 1995
Summary
11 beta-Hydroxysteroid dehydrogenase (11-HSD) is crucial for regulating steroid hormone activity. Key residues and structural elements are vital for its function, with potential implications for mineralocorticoid excess disorders.
Area of Science:
- Biochemistry
- Molecular Biology
- Endocrinology
Background:
- 11 beta-Hydroxysteroid dehydrogenase (11-HSD) regulates cortisol and cortisone levels, protecting the mineralocorticoid receptor.
- This enzyme is essential for aldosterone to act as a mineralocorticoid.
Purpose of the Study:
- To isolate and characterize the enzyme responsible for 11-HSD activity.
- To identify key functional domains and residues of the enzyme.
- To investigate the enzyme's role in apparent mineralocorticoid excess.
Main Methods:
- Isolation of 11-HSD enzyme from rat liver.
- Cloning of rat and human cDNA and genomic DNA.
- Site-directed mutagenesis to identify critical amino acid residues (Tyr-179, Lys-183).
- Analysis of patients with apparent mineralocorticoid excess for gene mutations.
Main Results:
- The 11-HSD enzyme was isolated and cloned from rat and human sources.
- Two conserved residues, Tyr-179 and Lys-183, were identified as essential for enzymatic activity.
- Deletion of the amino terminus or glycosylation sites abolished enzyme activity.
- No mutations were found in the studied gene in patients with apparent mineralocorticoid excess.
Conclusions:
- The characterized 11-HSD enzyme belongs to the short-chain dehydrogenase family.
- Specific residues and structural features are critical for 11-HSD enzymatic function.
- Apparent mineralocorticoid excess may be linked to a different, uncharacterized 11-HSD isozyme in the kidney.