RT Journal Article
SR Electronic
T1 Identification of a Ubiquitination-Target/Substrate-Interaction Domain of Cytochrome P-450 (CYP) 2E1
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP 118
OP 124
VO 28
IS 2
A1 Amit Banerjee
A1 Thomas A. Kocarek
A1 Raymond F. Novak
YR 2000
UL http://dmd.aspetjournals.org/content/28/2/118.abstract
AB Cytochrome P-450 (CYP) 2E1, the alcohol-inducible form of CYP, metabolizes a wide variety of endogenous substrates, therapeutic agents, protoxicants, and procarcinogens. CYP2E1 levels are post-transcriptionally elevated in response to certain xenobiotic inducers (e.g., pyridine), and proposed mechanisms include increased translational efficiency and protection of the enzyme from ubiquitin-dependent proteolysis. Molecular modeling of a predicted cytosolic domain of CYP2E1 resulted in identification of a putative ubiquitination-target/substrate-interaction structure (residues 317–340). An affinity-purified antibody reactive to this domain quenched CYP2E1 ubiquitination in a concentration-dependent manner in a rabbit reticulocyte lysate-based ubiquitination assay. The same antibody also inhibited rat liver microsomal chlorzoxazone 6-hydroxylase activity, a marker of CYP2E1 catalytic activity, in an equivalent concentration-dependent manner. These two observations suggest an association between the CYP2E1 cytosolic domain involved in catalysis and its serving as a target for ubiquitination. Thus, these results provide a plausible mechanistic explanation for the observation that substrate binding shields the CYP2E1 protein from turnover by the ubiquitin-proteasome-dependent machinery. The American Society for Pharmacology and Experimental Therapeutics