EMAIL THIS PAGE TO A FRIEND

American journal of physiology. Heart and circulatory physiology

Enhancement of closed-state inactivation in long QT syndrome sodium channel mutation DeltaKPQ.


PMID 12181125

Abstract

DeltaKPQ, a three amino acid [lysine (K), proline (P), glutamine (Q)] deletion mutation of the human cardiac Na channel (hH1), which is one cause of long QT syndrome (LQT3), has impaired inactivation resulting in a late sodium current. To better understand inactivation in DeltaKPQ, we applied a site-3 toxin anthopleurin A, which has been shown to inhibit inactivation from the open state with little or no effect on inactivation from the closed state(s) in wild-type hH1. In contrast to the effect of site-3 toxins on wild-type hH1, inactivation from closed state(s) in toxin-modified DeltaKPQ demonstrated a large negative shift in the Na channel availability curve of nearly -14 mV. Recovery from inactivation showed that toxin-modified DeltaKPQ channels recovered slightly faster than those in control, whereas development of inactivation at potentials negative to -80 mV showed that inactivation developed much more rapidly in toxin-modified DeltaKPQ channels compared with control. An explanation for our results is that closed-state inactivation in toxin-modified DeltaKPQ is enhanced by the mutated inactivation lid being positioned "closer" to its receptor resulting in an increased rate of association between the inactivation lid and its receptor.

Related Materials

Product #

Image

Description

Molecular Formula

Add to Cart

A7475 Anthopleurin-A, >88% (HPLC)
C220H326N64O67S6