High expression levels in cones of RGS9, the predominant GTPase accelerating protein of rods
High expression levels in cones of RGS9, the predominant GTPase accelerating protein of rods
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DOI：
10.1073/pnas.95.9.5351
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发表时间：
1998-04-28
影响因子：
11.1
通讯作者：
Wensel, TG
中科院分区：
文献类型：
--
作者：
Cowan, CW;Fariss, RN;Wensel, TG
RGS9 是异三聚体 G 蛋白 GTP 酶加速蛋白 (GAP) RGS 家族的成员。我们探索了它对哺乳动物视杆细胞和视锥细胞光感受器中 GTP 酶加速的贡献。当通过免疫耗竭从杆外节的去污剂提取物中特异性去除 RGS9 时，提取物几乎失去了所有可由 cGMP 磷酸二酯酶抑制亚基刺激的 GAP 活性。使用单克隆抗体和共聚焦显微镜进行的免疫定位显示，RGS9 在视锥细胞中的含量显着高于在视杆细胞中的水平。因此，RGS9是视杆细胞外节中GAP活性的主要来源，并且与视杆细胞相比，RGS9浓度成为哺乳动物视锥细胞更快的响应动力学和更低的灵敏度的潜在重要决定因素。
RGS9 is a member of the RGS family of GTPase accelerating proteins (GAPs) for heterotrimeric G proteins. We have explored its contribution to GTPase acceleration in mammalian rod and cone photoreceptors. When RGS9 was specifically removed from detergent extracts of rod outer segments by immunodepletion, the extracts lost nearly all of their GAP activity stimulatable by the inhibitory subunit of cGMP phosphodiesterase. Immunolocalization using monoclonal antibodies and confocal microscopy revealed that RGS9 is present in cones at significantly higher levels than in rods. Thus, RGS9 is the predominant source of GAP activity in rod outer segments, and RGS9 concentration emerges as a potentially important determinant of the faster response kinetics and lower sensitivity of mammalian cones, as compared with rods.