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Modulation of Kv2.1 channel gating and TEA sensitivity by distinct domains of SNAP-25.

Authors: He, Y  Kang, Y  Leung, YM  Xia, F  Gao, X  Xie, H  Gaisano, HY  Tsushima, RG 
Citation: He Y, etal., Biochem J. 2006 Jun 1;396(2):363-9.
Pubmed: (View Article at PubMed) PMID:16478442
DOI: Full-text: DOI:10.1042/BJ20051478

Distinct domains within the SNARE (soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor) proteins, STX1A (syntaxin 1A) and SNAP-25 (synaptosome-associated protein-25 kDa), regulate hormone secretion by their actions on the cell's exocytotic machinery, as well as voltage-gated Ca2+ and K+ channels. We examined the action of distinct domains within SNAP-25 on Kv2.1 (voltage gated K+ 2.1) channel gating. Dialysis of N-terminal SNAP-25 domains, S197 (SNAP-25(1-197)) and S180 (SNAP-25(1-180)), but not S206 (full-length SNAP-25(1-206)) increased the rate of Kv2.1 channel activation and slowed channel inactivation. Remarkably, these N-terminal SNAP-25 domains, acting on the Kv2.1 cytoplasmic N-terminus, potentiated the external TEA (tetraethylammonium)-mediated block of Kv2.1. To further examine whether these are effects of the channel pore domain, internal K+ was replaced with Na+ and external K+ was decreased from 4 to 1 mM, which decreased the IC50 of the TEA block from 6.8+/-0.9 mM to >100 mM. Under these conditions S180 completely restored TEA sensitivity (7.9+/-1.5 mM). SNAP-25 C-terminal domains, SNAP-25(198-206) and SNAP-25(181-197), had no effect on Kv2.1 gating kinetics. We conclude that different domains within SNAP-25 can form distinct complexes with Kv2.1 to execute a fine allosteric regulation of channel gating and the architecture of the outer pore structure in order to modulate cell excitability.


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RGD Object Information
RGD ID: 1581072
Created: 2006-09-14
Species: All species
Last Modified: 2006-09-14
Status: ACTIVE


RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.