Potassium channel toxin gamma-KTx 2.1

UniProtKB accession:  Q9BKB7

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UniProtKB description:  Blocks human and/or rat Kv11.1/KCNH2/ERG1, Kv11.2/KCNH6/ERG2 and Kv11.3/KCNH7/ERG3 by binding to channel outer vestibule (S5P domain) with a 1:1 stoichiometry. Inhibition data are the following: hERG1 (reversible, Kd=7.7 nM (PubMed:16497878), IC(50)=3.3 nM (PubMed:11136720), IC(50)=11.9 nM (PubMed:21205913)), rERG1 (reversible, Kd=19 nM) (PubMed:16497878), hERG2 (reversible, Kd=77 nM) (PubMed:16497878), rERG2 (irreversible, Kd=4.2 nM) (PubMed:16497878), hERG3 (reversible, Kd=11.5 nM) (PubMed:16497878) and rERG3 (reversible, Kd=747 nM) (PubMed:16497878) potassium channels. Has also a minimal effect on rat ELK1/KCNH4 potassium channels (9% inhibition at 100 nM (PubMed:15137031)). Both this toxin and CnErgTx1 (AC Q86QT3) share mechanism of action and have overlapping binding sites on ERG1 (PubMed:12719233). The potency of these two toxins is not affected by elevating potassium ion concentration from 2 to 98 mM (PubMed:12719233). In addition, at high toxin concentrations, block of ERG1 macroscopic currents by these two toxins is incomplete (88%) (PubMed:12719233). The blockade by this toxin is preferentially closed channel state-dependent, with a component of open, but not inactive state-dependent blockade (PubMed:12860380). This toxin produces a concentration-dependent prolongation of QTc in the isolated rabbit heart (16.3% at 100 nM) (PubMed:21205913).