一种人肝辅酶Ⅱ依赖性视黄醇脱氢酶剪接体cDNA的克隆及特征分析

在用RT-PCR法局部扩增人与小鼠肝脏635bp的NRDR DNA时，在人肝中发现了另一短序列PCR产物，克隆后测序显示其整个序列与NRDR cDNA编码区的前后序列完全一致。采用3’-Race和5’-Race方法，从人肝组织细胞中扩增得到两个全长cDNA，除1261bp的NRDR cDNA外，另一个为全长1003bp、编码区长为525bp的NRDRiso(GenBank登录号：AY071856)。数据库分析表明，NRDRiso编码区是由人NRDR8个外显子中的第1、2、3、7、8外显子选择性剪接而成。缺失的NRDR第4、5、6外显子共258bp，编码86个氨基酸。因此，与人NRDR的260个氨基酸残基相比，NRDRiso由174个氨基酸残基组成，分子量为18．6kDa，并且NRDRiso的组织表达与NRDR明显不同。

cDNA Cloning of a Short Isoform of Human Liver NADP(H)-Dependent Retinol Dehydrogenase/Reductase and Analysis of Its Characteristics

In this report we found a new short PCR product when we amplified a 635 bp of NRDR fragment by RT-PCR.With 3′-Race and 5′-Race,we obtained two full-length Cdna sequences from human liver tissue,one 1 261 bp NRDR Cdna,another 1 003 bp NRDR isoform (NRDRiso,GenBank accession number:AY071856).The NRDR gene comprises eight exons and seven introns.The NRDRiso Cdna is produced by alternative splicing of NRDR Cdna,with the removal of 4,5,6 exons composed of consecutive 258 bp.The open reading frames of the NRDRiso Cdna predict a single polypeptide of 174 amino acids with the calculated minimum molecular mass of 18.6 kDa.