Pittler S J, Lee A K, Altherr M R, Howard T A, Seldin M F, Hurwitz R L, Wasmuth J J, Baehr W
Department of Ophthalmology, Cullen Eye Institute, Baylor College of Medicine, Houston, Texas 77030.
J Biol Chem. 1992 Mar 25;267(9):6257-62.
We have determined the primary structures of the human and mouse retinal rod cGMP-gated cation channel by analysis of cDNA clones and amplified DNA. The open reading frames predicted polypeptides of 690 and 683 residues exhibiting 88% sequence similarity. Sequence comparison indicated that the rod channels consist of a variable 90-residue N-terminal region, a short highly charged segment rich in lysine and glutamate, and a 540-residue C-terminal portion that is well conserved in three mammalian species. Significant sequence similarity (59%) of the visual cGMP-gated channel to the olfactory cAMP-gated channel established the existence of a family of cyclic nucleotide-gated ion channel genes. RNA blot analysis revealed transcripts of 3.2 kilobases (kb) in human, mouse, and dog, 3.2, 4.6, and 5.2 kb in bovine, and 3.6 kb in fish. The human channel gene was mapped by polymerase chain reaction of somatic cell hybrid DNAs to chromosome 4 (p14-q13) near the centromere. The mouse channel gene locus (Cncg) was mapped by interspecific backcross haplotype analysis 0.9 centimorgan proximal of the Kit locus on chromosome 5.
我们通过对cDNA克隆和扩增DNA的分析，确定了人和小鼠视网膜视杆细胞环磷酸鸟苷门控阳离子通道的一级结构。开放阅读框预测的多肽分别含有690和683个残基，序列相似性为88%。序列比较表明，视杆细胞通道由一个可变的90个残基的N端区域、一个富含赖氨酸和谷氨酸的短的高电荷区段以及一个在三种哺乳动物中保守性良好的540个残基的C端部分组成。视觉环磷酸鸟苷门控通道与嗅觉环磷酸腺苷门控通道具有显著的序列相似性（59%），这证实了环状核苷酸门控离子通道基因家族的存在。RNA印迹分析显示，人、小鼠和犬的转录本为3.2千碱基（kb），牛的为3.2、4.6和5.2 kb，鱼的为3.6 kb。通过对体细胞杂交DNA进行聚合酶链反应，将人通道基因定位到4号染色体（p14-q13）着丝粒附近。通过种间回交单倍型分析，将小鼠通道基因位点（Cncg）定位到5号染色体上Kit位点近端0.9厘摩处。
