Overview
Alomone Labs Tertiapin-LQ inhibits Kir1.1 channels heterologously expressed in Xenopus oocytes.A continuous current trace of Kir1.1 channels was recorded at a holding potential of -80 mV. Channel activation was achieved by a continuous application of high K+ containing solution (indicated by the bottom bar). Kir1.1 currents are inhibited by increasing concentrations of Tertiapin-LQ (#STT-220), applied for 2 min each (100 nM, 200 nM, 500 nM and 1µM, as indicated by the top green bars).
Inward-rectifier K+ (Kir) channels play many important biological roles and are emerging as important therapeutic targets. Tertiapin (TPN), a toxin present in honey bee venom (Apis mellifera) inhibits certain subtypes of inward-rectifier K+ channels1. TPN is a highly compact peptide of 21 residues. Its C-terminal portion (histidine 12 to glycine 19) adopts an α-helical structure, whereas the N-terminal half acquires extended conformations. Two pairs of disulfide bonds help to hold the two parts together2. Tertiapin inhibits ROMK1 (Kir1.1) and G-protein-gated channel (GIRK1/4) (Kir3.1/3.4) channels with IC50 values of 8.6 and 2.0 nM respectively and is selective over Kir2.1 channels3. In accordance, it was shown to inhibit acetylcholine induced K+ currents in mammalian cardiomyocytes4.
Tertiapin-LQ is a tertiapin-Q derivative that blocks Kir1.1 channels. It does so by binding to the external vestibule of the K+-conduction pore that is formed by the linker between the first and second transmembrane (M1-M2) segments1.
