Aa1. A Novel Blocker of Shaker-B and IA K+ Channels.
Native Aa1 was originally isolated from Androctonus australis scorpion venom. Aa1 is a recombinant peptide expressed in and extracted from E. coli and purified to homogeneity. Native Aa1 blocks Shaker B channels expressed in Xenopus oocytes with IC50=4.5 μM. In addition the Aa1 toxin was shown to block the fast (A-type) K+ current in cerebellum granular cells (IC50 = 134 nM, or Kd = 150 nM). In both cases the block is non voltage dependent and does not affect kinetic parameters of the K+currents.
Ion Channel Modulators; K+ Channel Blockers.