Primary structure and expression of the human beta-subunit and related proteins of the rod photoreceptor cGMP-gated channel
Primary structure and expression of the human beta-subunit and related proteins of the rod photoreceptor cGMP-gated channel
复制标题
DOI：
10.1074/jbc.271.51.32968
复制
发表时间：
1996-12-20
影响因子：
4.8
通讯作者：
Molday, RS
中科院分区：
文献类型：
--
作者：
Colville, CA;Molday, RS
人类视杆感受器环核苷酸门控通道β亚基的全长cDNA编码一个1251个氨基酸(约140 kDa)的多肽，与牛的多肽一样，具有不寻常的二段结构。C-末端部分对应于先前报道的人类杆状通道的‘’亚基2‘’，并包含其他环核苷酸门控通道亚基的结构特征，包括六个假定的膜跨段、环核苷酸结合域、电压传感器基序和孔区。N端部分含有人类富含谷氨酸的蛋白质GARP。Western blotting表明，通过SDS-凝胶电泳法，天然和异源表达的人β亚基都以220 kDa多肽的形式异常迁移。另外两个GARP变体，全长GARP(f-GARP)和截短GARP(t-GARP)也存在于人、牛和大鼠的杆状外段，分别以120-140和55-62 kDa的多肽迁移。牛的f-GARP和t-GARP cDNAs分别编码590个氨基酸和299个氨基酸的蛋白质。F-GARP的前571个氨基酸和t-GARP的前291个氨基酸与牛β亚基对应的N-末端氨基酸序列相同。这两个GARP变体本身与杆状通道没有紧密的联系。这些结果表明，哺乳动物视杆细胞外段含有GARP的三种选择性剪接变体，其中一种构成视杆通道β亚基的N-末端部分。
The full-length cDNA for the beta-subunit of the human rod photoreceptor cyclic nucleotide-gated channel has been shown to encode a 1251-amino acid (similar to 140 kDa) polypeptide which, like its bovine counterpart, has an unusual bipartite structure. The C-terminal part corresponds to the previously reported ''subunit 2'' of the human rod channel and contains the structural features of other cyclic nucleotide-gated channel subunits including six putative membrane spanning segments, a cyclic nucleotide binding domain, a voltage sensor motif, and a pore region. The N-terminal part contains the human homolog of the bovine glutamic acid-rich protein called GARP. Western blots indicate that both the native and heterologously expressed human beta subunit migrate anomalously as a 220-kDa polypeptide by SDS-gel electrophoresis. Two other GARP variants, full-length GARP (f-GARP) and truncated GARP (t-GARP), are also present in human, bovine, and rat rod outer segments and migrate as 120-140- and 55-62-kDa polypeptides, respectively. The bovine f-GARP and t-GARP cDNAs code for proteins containing 590 amino acids and 299 amino acids, respectively. The first 571 amino acids of f-GARP and the first 291 amino acids of t-GARP are identical to the corresponding N-terminal amino acid sequence of the bovine beta-subunit. The two GARP variants, themselves, are not tightly associated with the rod channel. These results indicate that mammalian rod outer segments contain three alternatively spliced variants of GARP, one of which constitutes the N-terminal part of the rod channel beta-subunit.