Suzuki T, Suzuki N, Srivastava A S, Kurokawa T
Metabolism Section, National Research Institute of Aquaculture, Fisheries Agency, Nansei, Mie, 516-0193, Japan.
Biochem Biophys Res Commun. 2000 Apr 2;270(1):40-5. doi: 10.1006/bbrc.2000.2378.
cDNAs encoding two subtypes of the vitamin D receptor (VDR) are cloned from a teleost (flounder, Paralichthys olivaceus). This is the first report of VDR subtypes in fish. Flounder VDR (fVDR) a and b share 86% identity at the amino acid level. With human (h), rat, mouse, quail, and Xenopus VDRs, fVDRa shares 72%, 71%, 71%, 69%, and 71% identity, and fVDRb shares 70%, 69%, 69%, 67%, and 68% identity, respectively. The peptide sequences of the DNA-binding domain (DBD) and hormone-binding domain (HBD) of both subtypes have particularly high homology to those of the tetrapods; e.g. 92% identity for DBP and 74% for HBD between fVDRa and hVDR. In an evolutionary tree constructed with peptide sequences of VDRs and related members of the nuclear receptor superfamily, fVDRa and b are more closely related to each other than to other molecules, and situated in the cluster of VDRs at a position which corresponds well with the evolutional position of fish in the vertebrates. Additional independent genome duplication which is thought to have occurred in ray-finned fish phylogeny may explain the existence of two subtypes of VDR in flounder.
从一种硬骨鱼（比目鱼，褐牙鲆）中克隆出了编码维生素D受体（VDR）两种亚型的互补DNA。这是鱼类中VDR亚型的首次报道。比目鱼VDR（fVDR）a和b在氨基酸水平上有86%的同一性。与人类（h）、大鼠、小鼠、鹌鹑和非洲爪蟾的VDR相比，fVDRa分别有72%、71%、71%、69%和71%的同一性，fVDRb分别有70%、69%、69%、67%和68%的同一性。两种亚型的DNA结合结构域（DBD）和激素结合结构域（HBD）的肽序列与四足动物的相应序列具有特别高的同源性；例如，fVDRa和hVDR之间DBD的同一性为92%，HBD为74%。在用VDR的肽序列和核受体超家族的相关成员构建的进化树中，fVDRa和b彼此之间的关系比与其他分子的关系更密切，并且位于VDR簇中与鱼类在脊椎动物中的进化位置相当吻合的位置。被认为发生在辐鳍鱼类系统发育中的额外独立基因组复制可能解释了比目鱼中VDR两种亚型的存在。
