Phototransduction in transgenic mice after targeted deletion of the rod transducin α-subunit
Phototransduction in transgenic mice after targeted deletion of the rod transducin α-subunit
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DOI：
10.1073/pnas.250478897
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发表时间：
2000-12-05
影响因子：
11.1
通讯作者：
Lem, J
中科院分区：
文献类型：
--
作者：
Calvert, PD;Krasnoperova, NV;Lem, J
视网膜光感受器使用异三聚体：G蛋白转导素将视紫红质偶联到电光响应的生化级联反应。每个转导素亚基的几种亚型存在于视网膜中。虽然视杆细胞和视锥细胞似乎含有不同的转导素亚基，但尚不清楚特定细胞类型中的光转导是否严格依赖于每个亚基的单一形式。为了解决这个问题，我们删除了小鼠视杆细胞转导素铜亚基的基因。在半合子基因敲除小鼠中，视网膜转导蛋白cr亚基含量略有减少，但视网膜形态学和单视杆细胞生理学基本正常。在纯合子基因敲除小鼠中，随着年龄的增长发生轻度视网膜变性。视网膜电图中没有视杆细胞驱动的成分，而保留了视锥细胞驱动的成分。每一个通过单细胞记录检查的感光器都没有对闪光做出反应，只有一个例外。孤立的反应细胞是不敏感的，如预期的锥，但有一个杆状的光谱敏感性和闪光反应动力学是缓慢的，即使是杆。这些结果表明，大多数（如果不是全部的话）视杆在光转导中使用单一转导素类型。
Retinal photoreceptors use the heterotrimeric: G protein transducin to couple rhodopsin to a biochemical cascade that underlies the electrical photoresponse. Several isoforms of each transducin subunit are present in the retina. Although rods and cones seem to contain distinct transducin subunits, it is not known whether phototransduction in a given cell type depends strictly on a single form of each subunit. To approach this question, we have deleted the gene for the rod transducin cu-subunit in mice. In hemizygous knockout mice, there was a small reduction in retinal transducin cr-subunit content but retinal morphology and the physiology of single rods were largely normal. In homozygous knockout mice, a mild retinal degeneration occurred with age. Rod-driven components were absent from the electroretinogram, whereas cone-driven components were retained. Every photoreceptor examined by single-cell recording failed to respond to flashes, with one exception. The solitary responsive cell was insensitive, as expected for a cone, but had a rod-like spectral sensitivity and flash response kinetics that were slow, even for rods. These results indicate that most if not ail rods use a single transducin type in phototransduction.