Abstract
Ribbon synapses in retinal sensory neurons maintain large pools of readily releasable synaptic vesicles. This allows them to release several hundreds of vesicles per second at every presynaptic release site. The molecular components that cause this high transmitter release efficiency of ribbon synapses are unknown. In the present study, we identified and characterized two novel vertebrate complexins (CPXs), CPXs III and IV, that are the only CPX isoforms present in retinal ribbon synapses. CPXs III and IV are COOH-terminally farnesylated, and, like CPXs I and II, bind to SNAP receptor complexes. CPXs III and IV can functionally replace CPXs I and II, and their COOH-terminal farnesylation regulates their synaptic targeting and modulatory function in transmitter release. The novel CPXs III and IV may contribute to the unique release efficacy of retinal sensory neurons.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adaptor Proteins, Vesicular Transport
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Animals
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Cell Line
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Eye Proteins / genetics
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Eye Proteins / isolation & purification
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Eye Proteins / metabolism*
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Humans
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Membrane Proteins / genetics
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Membrane Proteins / isolation & purification
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Membrane Proteins / metabolism*
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Mice
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Molecular Sequence Data
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Nerve Tissue Proteins / genetics
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Nerve Tissue Proteins / isolation & purification
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Nerve Tissue Proteins / metabolism*
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Organelles / metabolism*
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Photoreceptor Cells / metabolism*
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Protein Binding / physiology
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Protein Prenylation / physiology
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Protein Structure, Tertiary / physiology
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Retina / metabolism*
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SNARE Proteins
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Sequence Homology, Amino Acid
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Sequence Homology, Nucleic Acid
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Synapses / metabolism*
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Synaptic Transmission / physiology
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Vesicular Transport Proteins / metabolism
Substances
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Adaptor Proteins, Vesicular Transport
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Eye Proteins
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Membrane Proteins
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Nerve Tissue Proteins
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SNARE Proteins
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Vesicular Transport Proteins
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complexin I
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complexin II
Associated data
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GENBANK/AY264290
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GENBANK/AY264291
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GENBANK/AY286501
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GENBANK/AY286502