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Updated: Aug 13, 2026

In Vitro Analysis of E3 Ubiquitin Ligase Function
Published on: May 14, 2021
Identification of a ubiquitination-Target/Substrate-interaction domain of cytochrome P-450 (CYP) 2E1
A Banerjee1, T A Kocarek, R F Novak
1Institute of Chemical Toxicology, Wayne State University, Detroit, Michigan 48201-2654, USA. abanerj@cmb.biosci.wayne.edu
Abstract:
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.
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