Calcium/Calmodulin Inhibits the Binding of Specific [125I]Omega-Conotoxin GVIA to Chick Brain Membranes |
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Authors: | Ichida Seiji Abe Junichi Yu-an Zhang Sugihara Kensuke Imoto Kouichiro Wada Tetsuyuki Sohma Hitoshi |
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Affiliation: | (1) Department of Biological Chemistry, Faculty of Pharmaceutical Sciences, Kinki University, Higashi-Osaka, 577-5802, Japan;(2) Department of Biological Chemistry, Faculty of Pharmaceutical Sciences, Kinki University, Higashi-Osaka, 577-5802, Japan;(3) Department of Biochemistry, Sapporo Medical University, School of Medicine, Chuo-Ku, Sapporo, 060-8556, Japan |
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Abstract: | The effect of Ca2+/calmodulin (CaM) on the specific binding of [125I]omega-conotoxin GVIA (125I--CTX) to crude membranes from chick brain was investigated. When we examined the effects of the activation of various endogenous protein kinases on specific [125I]-CTX binding to crude membranes, we observed that Ca2+/CaM had an inhibitory effect regardless of whether or not the standard medium contained ATP (0.5 mM). Ca2+/CaM also had an inhibitory effect in a simple binding-assay medium containing HEPES-HCl buffer, BSA, Ca2+ and CaM, and this effect was dependent on the concentration of Ca2+. The effect of Ca2+/CaM was attenuated by the CaM antagonists W-7 and CaM-kinase II fragment (290–309). An experiment with modified ELISA using purified anti -CTX antibody indicated that Ca2+/CaM did not affect the direct binding of [125I]-CTX and CaM. These results suggest that Ca2+/CaM either directly or indirectly affects specific [125I]-CTX binding sites, probably N-type Ca2+ channels in crude membranes from chick whole brain. |
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Keywords: | Anti omega-conotoxin antibody calmodulin N-type Ca2+ channels omega-conotoxin GVIA omega-conotoxin GVIA binding |
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