Synaptotagmin restores kinetic properties of a syntaxin-associated N-type voltage sensitive calcium channel.
The voltage sensitive N-type calcium channel interacts functionally and biochemically with synaptotagmin (p65). N-type channel interaction with p65 is demonstrated in the Xenopus oocyte expression system, where p65 alters the steady state voltage inactivation of the N-channel, and fully restores the syntaxin-modified current amplitude and inactivation kinetics in a calcium dependent manner. In agreement with the functional results, GST-p65 fusion protein binds to a cytosolic region, amino acids 710-1090 of the N-type channel (N-loop(710-1090)). The results of the combined approach provide a functional and biochemical basis for proposing that p65 interaction with the N-type channel brings p65 into a close association with a syntaxin-coupled channel. In turn, calcium entry through the liberated channel initiates fusion of the primed vesicles with the cell membrane at a short distance from the site of calcium entry.
Wiser
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Department of Biological Chemistry, The Hebrew University of Jerusalem, Israel.
Tobi
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Atlas
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D000818:Animals; D001921:Brain / Q000378:metabolism; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D015220:Calcium Channels / Q000096:biosynthesis / Q000187:drug effects / Q000502:physiology*; D002135:Calcium-Binding Proteins; D002462:Cell Membrane / Q000502:physiology; D003600:Cytosol / Q000502:physiology; D005260:Female; D005982:Glutathione Transferase / Q000096:biosynthesis; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008565:Membrane Proteins / Q000096:biosynthesis / Q000187:drug effects / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000187:drug effects / Q000502:physiology*; D009865:Oocytes / Q000502:physiology; D018408:Patch-Clamp Techniques; D050765:Qa-SNARE Proteins; D018075:RNA, Complementary; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000187:drug effects / Q000378:metabolism; D013324:Strontium / Q000494:pharmacology; D050825:Synaptosomal-Associated Protein 25; D050863:Synaptotagmin I; D050857:Synaptotagmins; D014982:Xenopus laevis
D015220:Calcium Channels; D002135:Calcium-Binding Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D050765:Qa-SNARE Proteins; D018075:RNA, Complementary; D011993:Recombinant Fusion Proteins; C494210:Snap25 protein, rat; D050825:Synaptosomal-Associated Protein 25; D050863:Synaptotagmin I; D050857:Synaptotagmins; D005982:Glutathione Transferase; D002118:Calcium; D013324:Strontium