Phosphorylation of 46-kappa Da protein of synaptic vesicle membranes is stimulated by GTP and Ca2+/calmodulin.
- Author:
Ah Ram KIM
1
;
Won Ho CHOI
;
Sae Ra LEE
;
Jun Sub KIM
;
Chan Young JEON
;
Jong Il KIM
;
Jae Bong KIM
;
Jae Yong LEE
;
Eung Gook KIM
;
Jae Bong PARK
Author Information
1. Department of Biochemistry, College of Medicine, Hallym University, Ockchon, Chunchon, Kangwon-do, Korea. jbpark@hallym.ac.kr
- Publication Type:Original Article ; Research Support, Non-U.S. Gov't
- Keywords:
calcium;
calmodulin;
guanosine triphos-phate;
phosphorylation;
rho GTP-binding proteins;
synapticvesicles
- MeSH:
Animals;
Calcium/*metabolism;
Calmodulin/*metabolism;
Carrier Proteins/*chemistry/*metabolism;
Guanine Nucleotide Dissociation Inhibitors/metabolism;
Guanosine Triphosphate/metabolism/*pharmacology;
Molecular Weight;
Monomeric GTP-Binding Proteins/metabolism;
Phosphorylation/drug effects;
Rats;
Recombinant Fusion Proteins/*chemistry/*metabolism;
Synaptic Membranes/chemistry/drug effects/*metabolism;
Synaptic Vesicles/chemistry/drug effects/*metabolism
- From:Experimental & Molecular Medicine
2002;34(6):434-443
- CountryRepublic of Korea
- Language:English
-
Abstract:
The release of neurotransmitter is regulated in the processes of membrane docking and membrane fusion between synaptic vesicles and presynaptic plasma membranes. Synaptic vesicles contain a diverse set of proteins that participate in these processes. Small GTP-binding proteins exist in the synaptic vesicles and are suggested to play roles for the regulation of neurotransmitter release. We have examined a possible role of GTP-binding proteins in the regulation of protein phosphorylation in the synaptic vesicles. GTPgammaS stimulated the phosphorylation of 46 kappa Da protein (p46) with pI value of 5.0-5.2, but GDPbetaS did not. The p46 was identified as protein interacting with C-kinase 1 (PICK-1) by MALDI-TOF mass spectroscopy analysis, and anti-PICK-1 antibody recognized the p46 spot on 2-dimensional gel electrophoresis. Rab guanine nucleotide dissociation inhibitor (RabGDI), which dissociates Rab proteins from SVs, did not affect phosphorylation of p46. Ca2+/ calmodulin (CaM), which causes the small GTP- binding proteins like Rab3A and RalA to dissociate from the membranes and stimulates CaM- dependnet protein kinase(s) and phosphatase, strongly stimulate the phosphorylation of p46 in the presence of cyclosporin A and cyclophylin. However, RhoGDI, which dissociates Rho proteins from membranes, reduced the phosphorylation of p46 to the extent of about 50%. These results support that p46 was PICK-1, and its phosphorylation was stimulated by GTP and Ca2+/CaM directly or indirectly through GTP-binding protein(s) and Ca2+/CaM effector protein(s). The phosphorylation of p46 (PICK-1) by GTP and Ca2+/CaM may be important for the regulation of transporters and neurosecretion.
