title: A possible role for CYP27 as a major renal mitochondrial 25-hydroxyvitamin D3 1 alpha-hydroxylase.
abstract: A mitochondrial cytochrome P450 fraction catalyzing 1 alpha- and 27-hydroxylation but not 24-hydroxylation of 25-hydroxyvitamin D3 was purified from pig kidney. The ratio between the 1 alpha- and 27-hydroxylase activities was the same in all purification steps including a side fraction. Attempts to separate the 1 alpha- and 27-hydroxylase activities were unsuccessful. A monoclonal antibody directed against purified pig liver CYP27 recognized a protein of the same apparent M(r) and immunoprecipitated both the 1 alpha- and 27-hydroxylase activities towards 25-hydroxyvitamin D3 in the purified kidney enzyme fraction as well as in a solubilized, crude cytochrome P450 extract considered to represent the major part of the 25-hydroxyvitamin D3 hydroxylases in kidney mitochondria. Taken together, the results from the purification and the experiments with CYP27 antibody, substrate inhibition, and recombinant expressed human liver CYP27 strongly indicate that CYP27 is able to catalyze 1 alpha-hydroxylation but not 24-hydroxylation of 25-hydroxyvitamin D3 in kidney. In conclusion, the results provide evidence for a role for CYP27 as a major renal mitochondrial 25-hydroxyvitamin D3 1 alpha-hydroxylase.
authors.affiliation: Department of Pharmaceutical Biosciences, University of Uppsala, Sweden.
authors.forename: Z
authors.initials: Z
authors.lastname: Araya
authors.forename: M
authors.initials: M
authors.lastname: Norlin
authors.forename: H
authors.initials: H
authors.lastname: Postlind
mesh_terms: D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D000818:Animals; D000911:Antibodies, Monoclonal; D015153:Blotting, Western; D053493:Cholestanetriol 26-Monooxygenase; D002852:Chromatography, Ion Exchange; D003001:Cloning, Molecular; D003577:Cytochrome P-450 Enzyme System / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli; D006801:Humans; D007672:Kidney Cortex / Q000201:enzymology*; D007700:Kinetics; D008928:Mitochondria / Q000201:enzymology*; D008930:Mitochondria, Liver / Q000201:enzymology*; D008970:Molecular Weight; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D013250:Steroid Hydroxylases / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D013552:Swine
chemical_list: D000911:Antibodies, Monoclonal; D011994:Recombinant Proteins; D003577:Cytochrome P-450 Enzyme System; D013250:Steroid Hydroxylases; C506831:CYP27A1 protein, human; D053493:Cholestanetriol 26-Monooxygenase; D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase