High expression levels in cones of RGS9, the predominant GTPase accelerating protein of rods
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- Christopher W. Cowan
- Verna and Marrs McLean Department of Biochemistry and Cell and Molecular Biology Graduate Program, Baylor College of Medicine, Houston, TX 77030; and Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98195-6485
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- Robert N. Fariss
- Verna and Marrs McLean Department of Biochemistry and Cell and Molecular Biology Graduate Program, Baylor College of Medicine, Houston, TX 77030; and Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98195-6485
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- Izabela Sokal
- Verna and Marrs McLean Department of Biochemistry and Cell and Molecular Biology Graduate Program, Baylor College of Medicine, Houston, TX 77030; and Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98195-6485
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- Krzysztof Palczewski
- Verna and Marrs McLean Department of Biochemistry and Cell and Molecular Biology Graduate Program, Baylor College of Medicine, Houston, TX 77030; and Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98195-6485
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- Theodore G. Wensel
- Verna and Marrs McLean Department of Biochemistry and Cell and Molecular Biology Graduate Program, Baylor College of Medicine, Houston, TX 77030; and Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98195-6485
説明
<jats:p>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.</jats:p>
収録刊行物
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- Proceedings of the National Academy of Sciences
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Proceedings of the National Academy of Sciences 95 (9), 5351-5356, 1998-04-28
Proceedings of the National Academy of Sciences