An NH(2)-terminal truncated cytochrome P450 CYP3A4 showing catalytic activity is present in the cytoplasm of human liver cells.
10.3858/emm.2008.40.2.254
- Author:
Songhee JEON
1
;
Keon Hee KIM
;
Chul Ho YUN
;
Boo Whan HONG
;
Yoon Seok CHANG
;
Ho Seong HAN
;
Yoo Seok YOON
;
Won Bum CHOI
;
Soyun KIM
;
Ai Young LEE
Author Information
1. Department of Dermatology, Dongguk University School of Medicine,Goyang 410-773, Korea. leeay@duih.org
- Publication Type:Short Communication ; Research Support, Non-U.S. Gov't
- Keywords:
cytochrome P-450 CYP3A;
cytoplasm;
enzymology;
microsomes, liver
- MeSH:
Blotting, Western;
Catalysis;
Cell Line;
Cytochrome P-450 CYP3A/chemistry/*metabolism;
Cytoplasm/*enzymology;
Humans;
Microsomes, Liver/*enzymology
- From:Experimental & Molecular Medicine
2008;40(2):254-260
- CountryRepublic of Korea
- Language:English
-
Abstract:
Cytochrome P450 3A4 (CYP3A4), is the dominant human liver hemoprotein enzyme localized in the endoplasmic reticulum (ER), and is responsible for the metabolism of more than 50% of clinically relevant drugs. While we were studying CYP3A4 expression and activity in human liver, we found that anti-CYP3A4 antibody cross-reacted with a lower band in liver cytoplasmic fraction. We assessed the activities of CYP3A4 and its truncated form in the microsomal and cytoplasmic fraction, respectively. In the cytoplasmic fraction, truncated CYP3A4 showed catalytic activity when reconstituted with NADPH-cytochrome P-450 reductase and cytochrome b5. In order to determine which site was deleted in the truncated form in vitro, we transfected cells with N-terminal tagged or C-terminal tagged human CYP3A4 cDNA. The truncated CYP3A4 is the N-terminal deleted form and was present in the soluble cytoplasmic fraction. Our result shows, for the first time, that N-terminal truncated, catalytically active CYP3A4 is present principally in the cytoplasm of human liver cells.
