Ca2+-sensitive regulation of E-type Ca2+ channel activity depends on an arginine-rich region in the cytosolic II-III loop
| Autor: | Udo Klöckner, Jérôme Leroy, Toni Schneider, Ning Qin, Alexey Pereverzev, Claire O. Malécot, Jürgen Hescheler, Gabriele Pfitzer, Rolf Vajna |
|---|---|
| Rok vydání: | 2003 |
| Předmět: |
Patch-Clamp Techniques
Arginine Protein subunit Kidney Transfection Cell Line Membrane Potentials Humans Patch clamp Egtazic Acid Chelating Agents chemistry.chemical_classification Chemistry General Neuroscience Kidney metabolism Embryo Mammalian Amino acid Protein Structure Tertiary Cytosol Protein Subunits Biochemistry Barium Mutation Biophysics Calcium Calcium Channels Intracellular |
| Zdroj: | The European journal of neuroscience. 18(4) |
| ISSN: | 0953-816X |
| Popis: | Ca2+-dependent regulation of L-type and P/Q-type Ca2+ channel activity is an important mechanism to control Ca2+ entry into excitable cells. Here we addressed the question whether the activity of E-type Ca2+ channels can also be controlled by Ca2+. Switching from Ba2+ to Ca2+ as charge carrier increased within 50 s, the density of currents observed in HEK-293 cells expressing a human Cav2.3d subunit and slowed down the inactivation kinetics. Furthermore, with Ca2+ as permeant ion, recovery from inactivation was accelerated, compared to the recovery process recorded under conditions where the accumulation of [Ca2+]i was prevented. In a Ba2+ containing bath solution the Ca2+-dependent changes of E-type channel activity could be induced by dialysing the cells with 1 micro m free [Ca2+]i suggesting that an elevation of [Ca2+]i is responsible for these effects. Deleting 19 amino acids in the intracellular II-III linker (exon 19) as part of an arginine-rich region, severely impairs the Ca2+ responsiveness of the expressed channels. Interestingly, deletion of an adjacent homologue arginine-rich region activates channel activity but now independently from [Ca2+]i. As a positive feedback-regulation of channel activity this novel activation mechanism might determine specific biological functions of E-type Ca2+ channels. |
| Databáze: | OpenAIRE |
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