Abstract
Rim1 was previously identified as a Rab3 effector localized to the presynaptic active zone in vertebrates. Here we demonstrate that C. elegans unc-10 mutants lacking Rim are viable, but exhibit behavioral and physiological defects that are more severe than those of Rab3 mutants. Rim is localized to synaptic sites in C. elegans, but the ultrastructure of the presynaptic densities is normal in Rim mutants. Moreover, normal levels of docked synaptic vesicles were observed in mutants, suggesting that Rim is not involved in the docking process. The level of fusion competent vesicles at release sites was reduced fivefold in Rim mutants, but calcium sensitivity of release events was unchanged. Furthermore, expression of a constitutively open form of syntaxin suppressed the physiological defects of Rim mutants, suggesting Rim normally acts to regulate conformational changes in syntaxin. These data suggest Rim acts after vesicle docking likely via regulating priming.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adaptor Proteins, Signal Transducing
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Amino Acid Motifs
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Amino Acid Sequence
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Animals
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Animals, Genetically Modified
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Caenorhabditis elegans / cytology
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Caenorhabditis elegans / genetics
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Caenorhabditis elegans / physiology*
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Caenorhabditis elegans Proteins*
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Carrier Proteins / chemistry
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Carrier Proteins / genetics
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Carrier Proteins / metabolism*
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Electrophysiology
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Genes, Helminth*
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Genes, Reporter
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Guanine Nucleotide Exchange Factors
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Helminth Proteins / genetics
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Helminth Proteins / metabolism*
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Intracellular Signaling Peptides and Proteins*
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Locomotion / physiology
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Membrane Proteins / genetics
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Membrane Proteins / metabolism
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Microscopy, Fluorescence
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Molecular Sequence Data
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Mutation
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Nerve Tissue Proteins / metabolism
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Neuromuscular Junction / physiology
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Neuromuscular Junction / ultrastructure
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Protein Structure, Tertiary
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Qa-SNARE Proteins
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Rabphilin-3A
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Sequence Alignment
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Synaptic Transmission / physiology
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Synaptic Vesicles / metabolism*
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Vesicular Transport Proteins
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Zinc Fingers
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rab GTP-Binding Proteins / metabolism
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rab3 GTP-Binding Proteins / metabolism
Substances
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Adaptor Proteins, Signal Transducing
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Caenorhabditis elegans Proteins
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Carrier Proteins
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Guanine Nucleotide Exchange Factors
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Helminth Proteins
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Intracellular Signaling Peptides and Proteins
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Membrane Proteins
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Nerve Tissue Proteins
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Qa-SNARE Proteins
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Rab3ip protein, rat
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Recombinant Fusion Proteins
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Vesicular Transport Proteins
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unc-10 protein, C elegans
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rab GTP-Binding Proteins
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rab3 GTP-Binding Proteins