Referenced in: none

Automatically associated channels: Nav1.5 , Slo1

Title: Slow-inactivation induced conformational change in domain 2-segment 6 of cardiac Na+ channel.

Authors: John P O'Reilly, Penny E Shockett

Journal, date & volume: Biochem. Biophys. Res. Commun., 2006 Jun 23 , 345, 59-66

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/16674915

Abstract
To examine conformational changes during slow inactivation involving domain 2-segment 6 (D2-S6) of human cardiac Na(+) channel (hNav1.5), we applied the substituted-cysteine accessibility method (SCAM) using methanethiosulfonate ethylammonium (MTSEA). We substituted cysteine (C) for native valine (V) at position 930 of D2-S6 in the MTSEA-resistant hNav1.5 mutant C373Y to produce the double mutant C373Y-V930C. Whole-cell Na(+) currents were recorded using patch-clamp techniques in transiently transfected HEK cells. In C373Y-V930C, we find that MTSEA (1.5 mM) applied in the closed state (-160 mV) has no significant effect on whole-cell Na(+) current, while MTSEA applied in the slow-inactivated state (prolonged depolarization at 0 mV) decreases current. We propose that D2-S6 in hNav1.5 undergoes molecular rearrangement during slow inactivation exposing the side chain of residue 930 such that it becomes accessible to modification by MTSEA.