Exocytosed protons feedback to suppress the Ca2+ current in mammalian cone photoreceptors. |
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Authors: | S H DeVries |
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Affiliation: | Department of Ophthalmology and Visual Science, Houston Health Science Center, University of Texas, Houston, TX 77030, USA. s-devries@northwestern.edu |
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Abstract: | A proton pump acidifies synaptic vesicles and provides the electrochemical gradient for transmitter uptake. Although external protons can modulate membrane voltage- and ligand-gated conductances, the fate of the protons released when vesicles fuse with the plasma membrane is unclear. In the dark, the glutamate-laden vesicles of cone photoreceptors fuse continuously with the plasma membrane. I now show that vesicular protons feed back to block the nearby calcium channels that mediate release. This local proton-mediated feedback is a novel mechanism through which neurons may regulate the release of transmitter. |
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