Molecular Cloning and Functional Characterization of a New Modulatory Cyclic Nucleotide-Gated Channel Subunit from Mouse Retina
Molecular Cloning and Functional Characterization of a New Modulatory Cyclic Nucleotide-Gated Channel Subunit from Mouse Retina
复制标题
DOI：
10.1523/jneurosci.20-04-01324.2000
复制
发表时间：
2000-02
期刊：
影响因子：
--
通讯作者：
Andrea Gerstner;X. Zong;F. Hofmann;M. Biel
中科院分区：
文献类型：
--
作者：
Andrea Gerstner;X. Zong;F. Hofmann;M. Biel
环核苷酸门控（CNG）通道在嗅觉和视觉信号转导中起关键作用。天然CNG通道是由主要α亚基（CNG 1 -3）和调节性β亚基（CNG 4 -5）组成的异聚体复合物，所述主要α亚基（CNG 1 -3）可以自身形成功能通道。单个α和β亚基联合收割机在视杆光感受器（CNG 1 + CNG 4）和嗅觉神经元（CNG 2 + CNG 4 + CNG 5）中形成CNG通道，其特征已得到表征。相比之下，迄今为止在视锥光感受器中仅鉴定出α亚基（CNG 3）。在这里，我们报告了一个新的CNG通道亚基（CNG 6）从小鼠视网膜的分子克隆。CNG 6的cDNA编码694个氨基酸的肽，预测分子量为80 kDa。在CNG通道亚基中，CNG 6与CNG 4 β亚基具有最高的总体相似性（47%序列同一性）。CNG 6转录本存在于视网膜感光细胞的一小部分中，也存在于睾丸中。人胚肾293细胞中CNG 6的异源表达未导致可检测的电流。然而，当与视锥细胞α亚基共表达时，CNG 6诱导了闪烁通道门控，减弱了细胞外Ca 2+存在时的外向整流，增加了对l-顺式地尔硫卓的敏感性，并增强了通道的cAMP功效。综上所述，数据表明CNG 6代表一种新的CNG通道β亚基，其可能与CNG 3 α亚基结合形成天然锥通道。
Cyclic nucleotide-gated (CNG) channels play a key role in olfactory and visual transduction. Native CNG channels are heteromeric complexes consisting of the principal α subunits (CNG1–3), which can form functional channels by themselves, and the modulatory β subunits (CNG4–5). The individual α and β subunits that combine to form the CNG channels in rod photoreceptors (CNG1 + CNG4) and olfactory neurons (CNG2 + CNG4 + CNG5) have been characterized. In contrast, only an α subunit (CNG3) has been identified so far in cone photoreceptors. Here we report the molecular cloning of a new CNG channel subunit (CNG6) from mouse retina. The cDNA of CNG6 encodes a peptide of 694 amino acids with a predicted molecular weight of 80 kDa. Among the CNG channel subunits, CNG6 has the highest overall similarity to the CNG4 β subunit (47% sequence identity). CNG6 transcripts are present in a small subset of retinal photoreceptor cells and also in testis. Heterologous expression of CNG6 in human embryonic kidney 293 cells did not lead to detectable currents. However, when coexpressed with the cone photoreceptor α subunit, CNG6 induced a flickering channel gating, weakened the outward rectification in the presence of extracellular Ca2+, increased the sensitivity forl-cis diltiazem, and enhanced the cAMP efficacy of the channel. Taken together, the data indicate that CNG6 represents a new CNG channel β subunit that may associate with the CNG3 α subunit to form the native cone channel.