Regulation of retinal transducin by C-terminal peptides of rhodopsin.
Regulation of retinal transducin by C-terminal peptides of rhodopsin.
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视紫红质 C 端肽对视网膜转导蛋白的调节。
DOI：
10.1042/bj2320669
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发表时间：
1985
期刊：
影响因子：
--
通讯作者：
Morrison,D
中科院分区：
文献类型：
--
作者：
Takemoto,DJ;Takemoto,LJ;Hansen,J;Morrison,D
转导蛋白是一种多亚基鸟嘌呤核苷酸结合蛋白，介导视紫红质和视网膜杆外节环GMP磷酸二酯酶之间的信号耦合。尽管转导素的T α亚基结合鸟嘌呤核苷酸并且是磷酸二酯酶的激活剂，但T β γ亚基可以起到将T α与光解视紫红质物理连接的作用。为了确定视紫红质与转导素的结合位点，我们合成了8个多肽（Rhod-1等）。其对应于视紫红质的C-末端区域以及几个外部环区域和一个内部环区域。测试这些肽对重建到耗尽的杆-外节盘膜中的纯化的转导素的恢复的GTdR活性的抑制。当转导蛋白与肽Rhod-1、Rhod-2和Rhod-3预孵育时，观察到GTdR活性的显著抑制。这些肽分别对应于视蛋白氨基酸残基332-339、324-331和317-321。对应于三个外环区域或C-末端残基341-348的肽不抑制重建的GT3活性。同样，Rhod-8，一种对应于视紫红质内环区域的肽，不抑制GT3活性。这些研究结果支持的概念，视紫红质的C-末端的这些特定区域作为transducin的识别位点。
Transducin is a multi-subunit guanine-nucleotide-binding protein that mediates signal coupling between rhodopsin and cyclic GMP phosphodiesterase in retinal rod outer segments. Whereas the T alpha subunit of transducin binds guanine nucleotides and is the activator of the phosphodiesterase, the T beta gamma subunit may function to link physically T alpha with photolysed rhodopsin. In order to determine the binding sites of rhodopsin to transducin, we have synthesized eight peptides (Rhod-1 etc.) that correspond to the C-terminal regions of rhodopsin and to several external and one internal loop region. These peptides were tested for their inhibition of restored GTPase activity of purified transducin reconstituted into depleted rod-outer-segment disc membranes. A marked inhibition of GTPase activity was observed when transducin was pre-incubated with peptides Rhod-1, Rhod-2 and Rhod-3. These peptides correspond to opsin amino acid residues 332-339, 324-331 and 317-321 respectively. Peptides corresponding to the three external loop regions or to the C-terminal residues 341-348 did not inhibit reconsituted GTPase activity. Likewise, Rhod-8, a peptide corresponding to an internal loop region of rhodopsin, did not inhibit GTPase activity. These findings support the concept that these specific regions of the C-terminus of rhodopsin serve as recognition sites for transducin.