1991 Fiscal Year Final Research Report Summary
Involvement and the Molecular Mechanisms of Inositol-1.4.5 Trisphosphate Receptor in the Expression of Neuronal Functions
| Project/Area Number |
02670107
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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 |
General medical chemistry
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| Research Institution | Osaka University |
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Principal Investigator |
NIINOBE Michio Institute for Protein Research, Osaka University, instructor, たんぱく質研究所, 助手 (80135748)
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| Project Period (FY) |
1990 – 1992
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| Keywords | IP_3 Receptor / IP_3 / IP_4 Binding Protein / IP_4 / IP_4結合蛋白質 |
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| Research Abstract |
1. Function of IP_3 Receptor Channel : The subunit structure of the IP_3 receptor protein was examined by cross-linking experiments. Agarose PAGE of the cross-linking material demonstrated that the cerebellar IP_3 receptor protein is composed of four noncovalently bound identical subunits in both purified and microsome-bound states. Reconstitution of the purified receptor into the planar lipid bilayer indicated channel activity with IP_3 dependent calcium conductance. And also in case of the reconstitution to a liposome, IP_3 dependent incorporation of a radiolabeled calcium was observed, and this incorporation was considerably inhibited by a monoclonal antibody which recognized carboxyterminal sequence of the receptor. These results suggest that the carboxyterminal structure is strongly involved in channel function and receives allosteric conformation change with a binding of IP_3.2. Biochemical and Immunohistochemical Analyses of IP_4 Binding Protein. There are at least three kinds of IP_4 binding protein in the mouse cerebellum. Among them IP_4 binding protein 1(IP_4BP1) was highly purified and investigated about various biochemical properties and detail of the localization in mouse brain. IP_4BP1 was composed of two molecular species, 140k and 65k which were highly homologous, as a complex. Kd value and optimal pH for IP_4 binding were 12nM and 8.0-9.0, respectively. Immunohistochemical analyses using a polyclonal antibody to the 140K molecule revealed that IP_4BP1 was localized in all of central nervous system, especially, external reticular layer and mitral cells of olfactory bulb, cell bodies and dendrites in pyramidal cells of cerebral cortex, radial fibrous layer of hippocampus, cell bodies and dendrites of Purkinje cells, and glomerulus in cerebellar cortex.
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Research Products
(6 results)
