一种新的短链脱氢/还原酶家族新成员:NADP(H)-依赖的视黄醇脱氢酶基因的克隆和分析

从牛的肝脏中快速抽提总RNA，根据GenBank已发表NADP(H)-依赖的视黄醇脱氢酶基因(NRDR)的cDNA序列，设计并合成特异引物，利用cDNA末端快速扩增(RACE)方法和反转录-聚合酶链式反应(RT-PCR)，得到牛肝内的NRDR cDNA的全长序列。经测序证实，牛肝NRDR的全长cDNA序列为1266bp，其开放读码框架在24～806bp，编码260个氨基酸(GenBank登录号：AF487454)。根据NRDR基因推导出的氨基酸序列与人、鼠、兔有高度同源性，并含有SDR超家族成员的两个高度保守的模序，在其C-端含有过氧化物酶体的靶向序列为SHL。结果表明，牛的NRDR应属于过氧化物酶体内SDR超家族成员并在维甲酸合成的限速步骤起作用的酶，也为维甲酸合成的传统通路提供一个补充。

Cloning and Analysis of NADP(H) -dependent Retinol Dehydrogenase/Reductase Gene:A Novel Member of Short-chain Dehydrogenase/Reductase

The total RNA was purified from bovine liver.According to the cDNA sequences of human,mouse and rabbit NADP(H)-dependent retinol dehydrogenase/reductase(NRDR) gene,the gene-specific primers were designed and synthesized.In this study,we cloned the full-length cDNA of bovine liver NRDR by rapid amplification of cDNA ends(RACE) and RT-PCR methods.The bovine NRDR cDNA is 1 266 bp and the ORF,like other NRDR cDNAs,is 783 bp,encoding 260 amino acid residues.The bovine NRDR exhibited the identity in amino acid sequence to those of human,mouse and rabbit NRDR.It contains short-chain dehydrogenase/reductase (SDR) conservative motif and the peroxisomal targeting singal(PTS1) sequence at their C-terminal.In conclusion,the bovine NRDR cDNA was successfully cloned with RACE methods and submitted to GenBank(AF487454),whose nucleotide sequence and the deduced amino acid sequence were analyzed with Bioinformatics,that belongs to a novel peroxisomal SDR superfamily and plays an important role in the rate-limiting step of synthesizing retinoic acid.This is the first report suggesting the SDR participation of mammalian peroxisomers in retinoid metabolism and it provides a reliable foundation to further investigate the biological function of this protein and retinoic acid biosynthesis.