Abstract
Ras-related small GTP-binding proteins execute many cellular functions, such as cell growth, differentiation, cytoskeletal reorganization, membrane trafficking, and membrane fusion. RalA belongs to the superfamily of Ras-related small GTP-binding proteins. Synaptic vesicles (SV) contain small GTP-binding proteins, where RalA, Rab3A, and Rab5A are the major GTP-binding proteins. It has been postulated that a cycling of these proteins between membrane-bound and soluble states is required for regulating cellular functions. Calmodulin (CaM) was found to dissociate Rab3A from SV membranes by forming a 1:1 complex with Ca2+/CaM. RalA was also found to be a Ca2+/CaM-binding protein. Therefore, we examined if Ca2+/CaM can also cause the RalA to dissociate from SV membranes. In this study, we identified that Ca2+/CaM dissociates RalA as well as Rab3A from synaptic vesicles.
Copyright 1999 Academic Press.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Brain / metabolism
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Calcium / pharmacology*
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Calmodulin / isolation & purification
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Calmodulin / pharmacology*
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Cattle
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GTP Phosphohydrolases / drug effects
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GTP Phosphohydrolases / metabolism*
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Guanine Nucleotide Dissociation Inhibitors / isolation & purification
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Guanine Nucleotide Dissociation Inhibitors / metabolism
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Membrane Fusion
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Rats
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Recombinant Fusion Proteins / metabolism
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Synaptic Membranes / drug effects
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Synaptic Membranes / metabolism*
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Synaptosomes / metabolism*
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rab3A GTP-Binding Protein / genetics
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rab3A GTP-Binding Protein / metabolism*
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rab5 GTP-Binding Proteins / genetics
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rab5 GTP-Binding Proteins / metabolism*
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ral GTP-Binding Proteins*
Substances
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Calmodulin
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GDP dissociation inhibitor 1
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Guanine Nucleotide Dissociation Inhibitors
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Recombinant Fusion Proteins
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GTP Phosphohydrolases
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Rala protein, rat
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rab3A GTP-Binding Protein
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rab5 GTP-Binding Proteins
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ral GTP-Binding Proteins
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Calcium