Dai D, Bai R, Hodgson E, Rose R L
NIEHS, National Institute of Health, Research Triangle Park, NC 27709, USA.
J Biochem Mol Toxicol. 2001;15(2):90-9. doi: 10.1002/jbt.4.
A full-length cDNA clone encoding a novel form of the cytochrome P450 3A subfamily (Cyp3a-25) has been isolated from a mouse liver cDNA library. The sequence contained 2010 base pairs and encoded a protein with 503 amino acids. The amino acid sequence shared greater identities with rat CYP3A18 (90%) and golden hamster CYP3A10 (81%) sequences than with known mouse sequences (Cyp3a-11, Cyp3a-13, Cyp3a-16, and Cyp3a-41 [68--70%]). CYP3A25 was expressed in the Escherichia coli PCWori(+) expression vector following slight modifications of the N- and C-terminals of the cDNA. The purified CYP3A25 was recognized on an immunoblot by CYP3A1 antibody and has a molecular weight of 50 kD. CYP3A25 was catalytically active in the 6 beta-hydroxylation of testosterone and the N-demethylation of benzphetamine and erythromycin. It was demonstrated by RT-PCR that the CYP3A25 mRNA is present in both fetal and adult tissues, including liver, lung, intestines, kidney, and brain. Northern blotting demonstrated that expression is greatest in the liver and small intestine.
从小鼠肝脏cDNA文库中分离出一个编码细胞色素P450 3A亚家族新形式（Cyp3a - 25）的全长cDNA克隆。该序列包含2010个碱基对，编码一个含有503个氨基酸的蛋白质。与已知的小鼠序列（Cyp3a - 11、Cyp3a - 13、Cyp3a - 16和Cyp3a - 41 [68 - 70%]）相比，该氨基酸序列与大鼠CYP3A18（90%）和金黄仓鼠CYP3A10（81%）序列具有更高的同源性。对cDNA的N端和C端进行轻微修饰后，CYP3A25在大肠杆菌PCWori(+)表达载体中表达。纯化后的CYP3A25在免疫印迹上能被CYP3A1抗体识别，分子量为50 kD。CYP3A25在睾酮的6β-羟基化以及苄非他明和红霉素的N-去甲基化反应中具有催化活性。RT-PCR结果表明，CYP3A25 mRNA在胎儿和成年组织中均有表达，包括肝脏、肺、肠道、肾脏和大脑。Northern印迹分析表明，其在肝脏和小肠中的表达量最高。
