Overview
- Redaelli, E. et al. (2010) J. Biol. Chem. 285, 4130.
Alomone Labs GsAF-I inhibits NaV1.7 currents in stably transfected HEK293T cells.A. Time course of GsAF-I (#STG-300) action on NaV1.7 peak currents. Peak current amplitudes were plotted as a function of time. Holding potential was -100 mV and currents were stimulated every 10 seconds by a voltage ramp of 50 msec from holding potential to 60 mV. 50 nM GsAF-I was perfused as indicated by the horizontal bar (green). B. Superimposed traces of NaV1.7 channel current in the absence (control) and presence of 50 nM (green) GsAF-I perfused during 2.5 min (taken from the experiment in A).
The tetrodotoxin (TTX)-sensitive Na+ channels are differentially distributed in the central and peripheral nervous systems, in skeletal muscle, and in cardiac muscle1.
Several venom-derived peptides are known to modify the gating properties of ion channels, and the study of their mechanisms of action is expected to contribute to the elucidation of the molecular motions associated with channel gating2. Tarantula venoms contain a library of interesting compounds, some of which are exquisite modulators of many types of ion channels. A large number of spider toxins have been demonstrated to modulate NaV channels3.
GsAF-I (also termed β-theraphotoxin-Gr1b) is a peptidyl toxin originally isolated from the venom of Grammostola rosea spider. This toxin is reported to block the following voltage-gated Na+ channels: NaV1.1, NaV1.2, NaV1.3, NaV1.4, NaV1.6 and NaV1.7 with respective IC50 values of 0.4, 0.6, 1.3, 0.3, 1.2 and 0.04 µM. In addition, the toxin blocks the hERG1 isoform with an IC50 value of 4.8 µM4.
