Blocks mouse voltage-gated potassium channels Kv1.3/KCNA3 (IC(50)=0.3-30 nM), when the channel is expressed in Jurkat T cells or in HEK293 cells (PubMed:31890149). Also shows a weaker inhibition on mKv1.2/KCNA2 (IC(50)=56.9 nM) and mKv1.1/KCNA1 (IC(50)=485 nM) (PubMed:31890149). Probably through the inhibition of both Kv1.2/KCNA2 and Kv1.3/KCNA3, the toxin also reduces the free calcium concentration in Jurkat T cells, inhibits the activation of Jurkat T cells and reduces the release of inflammatory cytokines interleukin-2, showing a strong immunosuppressant effect (PubMed:31890149). Expressed by the venom gland. Has the structural arrangement of an alpha-helix connected to a beta-sheet by disulfide bonds (CSalpha/beta). Does not block voltage-gated sodium channels Nav1.4/SCN4A, Nav1.5/SCN5A, and Nav1.7/SCN9A. Belongs to the short scorpion toxin superfamily. Potassium channel inhibitor family. Alpha-KTx 12 subfamily.