Disruption of Rab3-calmodulin interaction, but not other effector interactions, prevents Rab3 inhibition of exocytosis

被引:81
作者
Coppola, T
Perret-Menoud, V
Lüthi, S
Farnsworth, CC
Glomset, JA
Regazzi, R
机构
[1] Univ Lausanne, Inst Biol Cellulaire & Morphol, CH-1005 Lausanne, Switzerland
[2] Univ Washington, Howard Hughes Med Inst, Dept Med, Seattle, WA 98195 USA
[3] Univ Washington, Howard Hughes Med Inst, Dept Biochem, Seattle, WA 98195 USA
[4] Univ Washington, Reg Primate Res Ctr, Seattle, WA 98195 USA
关键词
GTP; insulin; neurotransmitter; secretion;
D O I
10.1093/emboj/18.21.5885
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Rab GTPases regulate membrane traffic between the cellular compartments of eukaryotic cells, Rab3 is associated with secretory vesicles of neuronal and endocrine cells and controls the Ca2+-triggered release of neurotransmitters and hormones. To clarify the mode of action of Rab3 we generated mutants of the GTPase that do not interact efficiently with its putative effecters Rabphilin and RIM, Surprisingly, these mutants transfected in PC12 cells were still capable of inhibiting Ca2+-evoked secretion. Rab3 was shown previously to bind to calmodulin in a Ca2+-dependent manner, By replacing two arginines conserved between Rab3 isoforms, we generated a mutant with a reduced affinity for calmodulin, This mutant retained the capacity to interact with the Rab3 regulatory proteins, Rabphilin, RIM, Mss4 and RabGDI, and was correctly targeted to dense-core secretory granules, However, replacement of the two arginines abolished the ability of the GTP-bound form of Rab3 to inhibit exocytosis of catecholamine- and insulin-secreting cells. We propose that a Rab3-calmodulin complex generated by elevated Ca2+ concentrations mediated at least some of the effects of the GTPase and limited the number of exocytotic events that occurred in response to secretory stimuli.
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页码:5885 / 5891
页数:7
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