Kappa-theraphotoxin-Cg1a 1

UniProtKB accession:  P0C247

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UniProtKB description:  This toxin acts as a voltage-dependent gating-modifier (PubMed:25240294). It inhibits the sodium conductance (IC(50)=124 nM) and slows the fast inactivation (EC(50)=1180 nM) of Nav1.5/SCN5A (PubMed:17176080, PubMed:25240294). It significantly shifts the activation to more depolarized voltages and decreases the deactivation of Nav1.5 currents upon extreme depolarization, but only slightly affects voltage-dependence of steady-state inactivation (PubMed:17176080, PubMed:25240294). In addition, this toxin causes an approximately five-fold decrease in the rate of recovery from inactivation and an approximately 1.9-fold reduction in the closed-state inactivation rate (PubMed:25240294). This toxin integrates the functions of site 3 toxins (alpha-scorpion toxins) with site 4 toxins (beta-scorpion and spider toxins) by targeting multiple sites on Nav1.5 (PubMed:25240294). Also shows inhibition of voltage-gated potassium channels (5 uM completely inhibits Kv2.1/KCNB1, whereas 5 uM moderately inhibits Kv4.2/KCND2 Kv4.1/KCND1 channels) (PubMed:17176080).