de Morais S M, Schweikl H, Blaisdell J, Goldstein J A
National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709.
Biochem Biophys Res Commun. 1993 Jul 15;194(1):194-201. doi: 10.1006/bbrc.1993.1803.
There is a genetic polymorphism in humans in the metabolism of S-mephenytoin which has been suggested to be mediated by either CYP2C18 or CYP2C9. We have isolated genomic clones for CYP2C9 and CYP2C18 from the liver of an individual phenotyped in vitro as an extensive metabolizer of S-mephenytoin. Analysis of the genes reveals nine coding exons spanning approximately 55 kb. The intron-exon organization was similar to that of other members of the CYP2C subfamily. Analysis of 2200 bp of 5' upstream sequence for CYP2C9 and 1300 bp 5' upstream sequence for CYP2C18 reveals canonical TATA boxes situated 57 bp upstream from the first codon, multiple consensus sequences for glucocorticoid regulatory elements, and identification of a 15 base sequence with high homology to a 5'-flanking sequence responsible for barbiturate-inducible expression of P450BM-3 in Bacillus megaterium. The upstream region for CYP2C9 was highly homologous (75%) to that of human CYP2C8 through most of the 2200 bp sequenced, but the upstream region of CYP2C18 was similar to CYP2C8 and CYP2C9 for only the first 200 bases. The availability of the sequences of the upstream regions and intron-exon junctions of CYP2C9 and CYP2C18 will allow future analysis of these genes in humans which differ in their ability to metabolize S-mephenytoin and other drugs.
人类中S-美芬妥因的代谢存在遗传多态性，有人认为这是由CYP2C18或CYP2C9介导的。我们从一名在体外被表型鉴定为S-美芬妥因广泛代谢者的个体肝脏中分离出了CYP2C9和CYP2C18的基因组克隆。对这些基因的分析揭示了9个编码外显子，跨度约为55kb。内含子-外显子组织与CYP2C亚家族的其他成员相似。对CYP2C9的2200bp 5'上游序列和CYP2C18的1300bp 5'上游序列进行分析，发现了位于第一个密码子上游57bp处的典型TATA盒、多个糖皮质激素调节元件的共有序列，并鉴定出一个与巨大芽孢杆菌中负责巴比妥酸盐诱导的P450BM-3表达的5'-侧翼序列具有高度同源性的15个碱基序列。在测序的2200bp的大部分区域，CYP2C9的上游区域与人类CYP2C8的上游区域高度同源（75%），但CYP2C18的上游区域仅在前200个碱基与CYP2C8和CYP2C9相似。CYP2C9和CYP2C18上游区域及内含子-外显子连接序列的可得性将有助于未来对这些基因在人类中的分析，这些基因在代谢S-美芬妥因和其他药物的能力上存在差异。
