Dissociation of RalA from synaptic membranes by Ca2+/calmodulin.
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.
Park
J B
JB
Department of Biochemistry, College of Medicine, Hallym University, Chunchon, Kang-Won Do, 200-702. jbpark@sun.hallym.ac.kr
Lee
J Y
JY
Kim
J W
JW
D000818:Animals; D001921:Brain / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology*; D002147:Calmodulin / Q000302:isolation & purification / Q000494:pharmacology*; D002417:Cattle; D020558:GTP Phosphohydrolases / Q000187:drug effects / Q000378:metabolism*; D020730:Guanine Nucleotide Dissociation Inhibitors / Q000302:isolation & purification / Q000378:metabolism; D008561:Membrane Fusion; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013570:Synaptic Membranes / Q000187:drug effects / Q000378:metabolism*; D013574:Synaptosomes / Q000378:metabolism*; D020826:rab3A GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*; D020696:rab5 GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020725:ral GTP-Binding Proteins
D002147:Calmodulin; C086796:GDP dissociation inhibitor 1; D020730:Guanine Nucleotide Dissociation Inhibitors; D011993:Recombinant Fusion Proteins; D020558:GTP Phosphohydrolases; C492197:Rala protein, rat; D020826:rab3A GTP-Binding Protein; D020696:rab5 GTP-Binding Proteins; D020725:ral GTP-Binding Proteins; D002118:Calcium