ISSN:
1573-4943
Keywords:
3-hydroxy-3-methylglutaryl Coenzyme A reductase
;
phosphorylation-dephosphorylation
;
phosphorylation sites
;
phosphoserine
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Microsomal 3-hydroxy-3-methylglutaryl Coenzyme A reductase (EC 1.1.1.34) was inactivated by [γ-32P]ATP in the presence of endogenous reductase kinases, solubilized, and purified 575-fold with retention of32P to a state where phosphoreductase was the only32P-labeled protein present.32P comigrated with reductase activity under nondenaturing conditions (polyacrylamide gets, isoelectric focusing gels) and with reductase monomer under denaturing conditions (sodium dodecyl sulfate-polyacrylamide gels). Polyfunctional antibody to homogeneous reductase precipitated all of the32P present. The phosphate-reductase bond was acid-stable and base-labile. Following acid hydrolysis and high-voltage electrophoresis,32P label migrated solely with phosphoserine and inorganic orthophosphate. Exhaustive (〉100 h) tryptic digestion of phosphoreductase denatured in 2 M urea yielded two major phosphorylated components as judged by high-performance liquid chromatography or Sephadex G-25 chromatography. 3-Hydroxy-3-methylglutaryl Coenzyme A reductase inactivated in the microsomal state by [γ-32P]ATP is thus phosphorylated exclusively at seryl residues and contains two structurally distinct phosphorylation sites.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01025355
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