The Experts below are selected from a list of 196413 Experts worldwide ranked by ideXlab platform
Hitoshi Sohma - One of the best experts on this subject based on the ideXlab platform.
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characteristics of the inhibitory effect of calmodulin on specific 125i omega conotoxin gvia binding to crude membranes from chick brain
Neurochemical Research, 2000Co-Authors: Seiji Ichida, Kensuke Sugihara, Kouichiro Imoto, Tetsuyuki Wada, Norihisa Fujita, Zhang Yuan, Hitoshi SohmaAbstract:The characteristics of the inhibitory effect of calcium ion (Ca2+)/calmodulin (Cam) on specific [125I]-omega-conotoxin GVIA (125I-ω-CTX) binding and on the labeling of 125I-ω-CTX to crude membranes from chick brain were investigated. The inhibitory effect of Ca2+/Cam depended on the concentrations of free Ca2+ and Cam. The IC50 values for free Ca2+ and Cam were about 2.0 × 10−8 M and 3.0 μg protein/ml, respectively. The inhibitory effect of Ca2+/Cam was attenuated by the Cam antagonists W-7, prenylamine and Cam-kinase II fragment (290–309), but not by the calcineurin inhibitor FK506. Ca2+/Cam also inhibited the labeling of a 135-kDa band (which was considered to be part of N-type Ca2+ channel α1 subunits) with 125I-ω-CTX using a cross-linker. These results suggest that Ca2+/Cam affects specific 125I-ω-CTX binding sites, probably N-type Ca2+ channel α1 subunits, in crude membranes from chick whole brain.
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calcium calmodulin inhibits the binding of specific 125i omega conotoxin gvia to chick brain membranes
Neurochemical Research, 2000Co-Authors: Seiji Ichida, Kensuke Sugihara, Kouichiro Imoto, Tetsuyuki Wada, Zhang Yuan, Hitoshi SohmaAbstract:The effect of Ca2+/calmodulin (Cam) on the specific binding of [125I]omega-conotoxin GVIA (125I-ω-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]ω-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 ω-CTX antibody indicated that Ca2+/Cam did not affect the direct binding of [125I]ω-CTX and Cam. These results suggest that Ca2+/Cam either directly or indirectly affects specific [125I]ω-CTX binding sites, probably N-type Ca2+ channels in crude membranes from chick whole brain.
Seiji Ichida - One of the best experts on this subject based on the ideXlab platform.
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characteristics of the inhibitory effect of calmodulin on specific 125i omega conotoxin gvia binding to crude membranes from chick brain
Neurochemical Research, 2000Co-Authors: Seiji Ichida, Kensuke Sugihara, Kouichiro Imoto, Tetsuyuki Wada, Norihisa Fujita, Zhang Yuan, Hitoshi SohmaAbstract:The characteristics of the inhibitory effect of calcium ion (Ca2+)/calmodulin (Cam) on specific [125I]-omega-conotoxin GVIA (125I-ω-CTX) binding and on the labeling of 125I-ω-CTX to crude membranes from chick brain were investigated. The inhibitory effect of Ca2+/Cam depended on the concentrations of free Ca2+ and Cam. The IC50 values for free Ca2+ and Cam were about 2.0 × 10−8 M and 3.0 μg protein/ml, respectively. The inhibitory effect of Ca2+/Cam was attenuated by the Cam antagonists W-7, prenylamine and Cam-kinase II fragment (290–309), but not by the calcineurin inhibitor FK506. Ca2+/Cam also inhibited the labeling of a 135-kDa band (which was considered to be part of N-type Ca2+ channel α1 subunits) with 125I-ω-CTX using a cross-linker. These results suggest that Ca2+/Cam affects specific 125I-ω-CTX binding sites, probably N-type Ca2+ channel α1 subunits, in crude membranes from chick whole brain.
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calcium calmodulin inhibits the binding of specific 125i omega conotoxin gvia to chick brain membranes
Neurochemical Research, 2000Co-Authors: Seiji Ichida, Kensuke Sugihara, Kouichiro Imoto, Tetsuyuki Wada, Zhang Yuan, Hitoshi SohmaAbstract:The effect of Ca2+/calmodulin (Cam) on the specific binding of [125I]omega-conotoxin GVIA (125I-ω-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]ω-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 ω-CTX antibody indicated that Ca2+/Cam did not affect the direct binding of [125I]ω-CTX and Cam. These results suggest that Ca2+/Cam either directly or indirectly affects specific [125I]ω-CTX binding sites, probably N-type Ca2+ channels in crude membranes from chick whole brain.
Michael X Zhu - One of the best experts on this subject based on the ideXlab platform.
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activation of trp3 by inositol 1 4 5 trisphosphate receptors through displacement of inhibitory calmodulin from a common binding domain
Proceedings of the National Academy of Sciences of the United States of America, 2001Co-Authors: Zongming Zhang, Jisen Tang, Svetlana B Tikunova, David J Johnson, Zhangguo Chen, Ning Qin, Alexander Dietrich, Enrico Stefani, Lutz Birnbaumer, Michael X ZhuAbstract:Mammalian homologues of Drosophila Trp form plasma membrane channels that mediate Ca2+ influx in response to activation of phospholipase C and internal Ca2+ store depletion. Previous studies showed that human Trp3 is activated by inositol 1,4,5-trisphosphate (IP3) receptors (IP3Rs) and identified interacting domains, one on Trp and two on IP3R. We now find that Trp3 binds Ca2+-calmodulin (Ca2+/Cam) at a site that overlaps with the IP3R binding domain. Using patch-clamp recordings from inside-out patches, we further show that Trp3 has a high intrinsic activity that is suppressed by Ca2+/Cam under resting conditions, and that Trp3 is activated by the following: a Trp-binding peptide from IP3R that displaces Cam from Trp3, a myosin light chain kinase Ca2+/Cam binding peptide that prevents Cam from binding to Trp3, and calmidazolium, an inactivator of Ca2+/Cam. We conclude that inhibition of the inhibitory action of Cam is a key step of Trp3 channel activation by IP3Rs.
Humbert De Smedt - One of the best experts on this subject based on the ideXlab platform.
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localization and function of a calmodulin apocalmodulin binding domain in the n terminal part of the type 1 inositol 1 4 5 trisphosphate receptor
Biochemical Journal, 2002Co-Authors: Ilse Sienaert, Nael Nadif Kasri, Sara Vanlingen, Jan B Parys, Geert Callewaert, Ludwig Missiaen, Humbert De SmedtAbstract:Calmodulin (Cam) is a ubiquitous protein that plays a critical role in regulating cellular functions by altering the activity of a large number of proteins, including the d-myo-inositol 1,4,5-trisphosphate (IP3) receptor (IP3R). Cam inhibits IP3 binding in both the presence and absence of Ca2+ and IP3-induced Ca2+ release in the presence of Ca2+. We have now mapped and characterized a Ca2+-independent Cam-binding site in the N-terminal part of the type 1 IP3R (IP3R1). This site could be responsible for the inhibitory effects of Cam on IP3 binding. We therefore expressed the N-terminal 581 amino acids of IP3R1 as a His-tagged recombinant protein, containing the functional IP3-binding pocket. We showed that Cam, both in the presence and absence of Ca2+, inhibited IP3 binding to this recombinant protein with an IC50 of approx. 2 microM. Deletion of the N-terminal 225 amino acids completely abolished the effects of both Ca2+ and Cam on IP3 binding. We mapped the Ca2+-independent Cam-binding site to a recombinant glutathione S-transferase fusion protein containing the first 159 amino acids of IP3R1 and then made different synthetic peptides overlapping this region. We demonstrated that two synthetic peptides matching amino acids 49-81 and 106-128 bound Cam independently of Ca2+ and could reverse the inhibition of IP3 binding caused by Cam. This suggests that these sequences are components of a discontinuous Ca2+-independent Cam-binding domain, which is probably involved in the inhibition of IP3 binding by Cam.
Kensuke Sugihara - One of the best experts on this subject based on the ideXlab platform.
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characteristics of the inhibitory effect of calmodulin on specific 125i omega conotoxin gvia binding to crude membranes from chick brain
Neurochemical Research, 2000Co-Authors: Seiji Ichida, Kensuke Sugihara, Kouichiro Imoto, Tetsuyuki Wada, Norihisa Fujita, Zhang Yuan, Hitoshi SohmaAbstract:The characteristics of the inhibitory effect of calcium ion (Ca2+)/calmodulin (Cam) on specific [125I]-omega-conotoxin GVIA (125I-ω-CTX) binding and on the labeling of 125I-ω-CTX to crude membranes from chick brain were investigated. The inhibitory effect of Ca2+/Cam depended on the concentrations of free Ca2+ and Cam. The IC50 values for free Ca2+ and Cam were about 2.0 × 10−8 M and 3.0 μg protein/ml, respectively. The inhibitory effect of Ca2+/Cam was attenuated by the Cam antagonists W-7, prenylamine and Cam-kinase II fragment (290–309), but not by the calcineurin inhibitor FK506. Ca2+/Cam also inhibited the labeling of a 135-kDa band (which was considered to be part of N-type Ca2+ channel α1 subunits) with 125I-ω-CTX using a cross-linker. These results suggest that Ca2+/Cam affects specific 125I-ω-CTX binding sites, probably N-type Ca2+ channel α1 subunits, in crude membranes from chick whole brain.
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calcium calmodulin inhibits the binding of specific 125i omega conotoxin gvia to chick brain membranes
Neurochemical Research, 2000Co-Authors: Seiji Ichida, Kensuke Sugihara, Kouichiro Imoto, Tetsuyuki Wada, Zhang Yuan, Hitoshi SohmaAbstract:The effect of Ca2+/calmodulin (Cam) on the specific binding of [125I]omega-conotoxin GVIA (125I-ω-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]ω-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 ω-CTX antibody indicated that Ca2+/Cam did not affect the direct binding of [125I]ω-CTX and Cam. These results suggest that Ca2+/Cam either directly or indirectly affects specific [125I]ω-CTX binding sites, probably N-type Ca2+ channels in crude membranes from chick whole brain.
