1987 Fiscal Year Final Research Report Summary
Identification of Na Ion Chennel Protein in Frog Rod Outer Segments.
| Project/Area Number |
61580223
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
分子遺伝学・分子生理学
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| Research Institution | Faculty of Natural Science, Naruto Univ. of Education. |
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Principal Investigator |
SHINOZAWA Takao Associate Professor, Faculty of Natural Sci. Naruto Univ., 自然系理科, 助教授 (30025449)
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| Co-Investigator(Kenkyū-buntansha) |
SOKABE Masahiro Associate Professor, Faculty of Medicine, Nagoya Univ., 医学部, 助教授 (10093428)
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| Project Period (FY) |
1986 – 1987
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| Keywords | Photoreceptor / Rod Outer Segments / Cyclic GMP Binding Protein / Na Ion Channel / 視興奮 |
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| Research Abstract |
For the identification of cGMP-sensitive ion channel protein in frog rod outer segments (ROS), we analyzed cGMP binding proteins in the ROS by means of photoaffinity labeling with [^3H]cGMP. we found four cGMP binding proteins (Mws 250K, 100K, 92K and 53K). Mw 250K protein was an integral-membrane protein. 250K Protein has carbohydrate moiety. The amount of 250K Protein per single rod outer segment was estimated to be 9.0 x 10_6 molecules. Light-dependent phosphorylation of 250K Protein with <gamma>-^<32>PLATP was observed. Mws 100K and 92K proteins were peripheral-membrane proteins, corresponding to cGMP phosphodiesterase. Mw 53K protein was a soluble protein. Incorporation of a membrane protein fraction of frog ROS into a planar lipid bilayer displayed the presence of, at least, three kinds of ion channel activities; two of them were related to cGMP.
Concerning the identification of cGMP-sensitive ion channel protein, Cooket al (1987) reported a protein with Mw of 63K and Matesic & Li
… More
ebmann (1987) reported a protein with Mw 39K. We suppose the discrepancy in these reports are related on the difference in their experimental conditions or on the presence of different species of cGMP-sensitive ion channels. In the later point, we detected other cGMP binding protein with Mw 66K in the presence of Ca^<2+> in frog rod outer segments. This 66K protein may be the same protein as Mw 63K protein reported by Cook et al. We have partially purified 250K protein (approximately 50% purity) by the solubilization with use of CHAPS and the sucrose density gradient centrifugation. We could detect the ion channel activity in this 250K protein fraction. For the elucidation of the relationships between the 250K protein and 66K(63K) protein, we etracted 250K protein from the gel of SDSPAGE. The Mw of extracted 250K protein did not changed by the boiling in the SDS solution. Therefore, 250K protein is not an oligomer of 66K(63K) protein.
The results described above support the idea that 250K protein is one of the cGMP-sensitive ion channel protein in the vertebrate photoreceptor. Less
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[Publications] Yoshizawa,T., Shinozawa,T., Shichida,Y.,Matsuoka,S., Ioshida,H., Kandori,H. & Sokabe,M.: The Transduction Mechanism of Light Information in Rod Outer Segment.VNU Science Press. The Netherland., 75-84 (1987)
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