Monkawa T, Yoshida T, Wakino S, Shinki T, Anazawa H, Deluca H F, Suda T, Hayashi M, Saruta T
School of Medicine, Keio University, Tokyo, Japan.
Biochem Biophys Res Commun. 1997 Oct 20;239(2):527-33. doi: 10.1006/bbrc.1997.7508.
The 25-hydroxyvitamin D3 1 alpha-hydroxylase (1 alpha-hydroxylase) is a cytochrome P450 enzyme that catalyzes the conversion of 25-hydroxyvitamin D3 to 1 alpha,25-dihydroxyvitamin D3. This enzyme plays an important role in calcium homeostasis. Here we report the molecular cloning of cDNA and gene for human 1 alpha-hydroxylase. The cDNA clone was obtained from a human kidney cDNA library by cross-hybridization with a previously cloned rat cDNA probe. The cDNA consists of 2469 bp and encodes a protein of 508 amino acids that shows 82.5% sequence identity with the rat enzyme. A computer-aided homology search revealed that 1 alpha-hydroxylase shares a relatively high homology with vitamin D3 25-hydroxylase (about 40% amino acid identity). Northern blot analysis showed that the 2.5-kb mRNA is most abundant in kidney. The gene for human 1 alpha-hydroxylase spans approximately 6 kb, is composed of nine exons, and is present as a single copy. This molecular cloning makes it possible to investigate the genetic mechanism of diseases related to calcium metabolism, including vitamin D-dependency rickets type I.
25-羟维生素D3 1α-羟化酶（1α-羟化酶）是一种细胞色素P450酶，可催化25-羟维生素D3转化为1α,25-二羟维生素D3。该酶在钙稳态中起重要作用。在此，我们报道了人1α-羟化酶的cDNA和基因的分子克隆。通过与先前克隆的大鼠cDNA探针进行交叉杂交，从人肾cDNA文库中获得了cDNA克隆。该cDNA由2469个碱基对组成，编码一个508个氨基酸的蛋白质，与大鼠酶的序列同一性为82.5%。计算机辅助同源性搜索显示，1α-羟化酶与维生素D3 25-羟化酶具有较高的同源性（约40%的氨基酸同一性）。Northern印迹分析表明，2.5kb的mRNA在肾脏中最为丰富。人1α-羟化酶基因跨度约6kb，由9个外显子组成，以单拷贝形式存在。这种分子克隆使得研究与钙代谢相关疾病的遗传机制成为可能，包括I型维生素D依赖性佝偻病。
