Shows weak blocking activity on voltage-gated potassium channels Kv10.1/KCNH1/EAG1 (IC(50)=26 uM), Kv1.2/KCNA2 (Kd=150 uM), Kv1.3/KCNA3 (Kd=40 uM), Kv1.6/KCNA3 (16.6% inhibition at 40 uM toxin) (PubMed:12034709, PubMed:23726856, PubMed:27578329). The block is dose-dependent, voltage-independent, and reversible (PubMed:12034709). Also shows a weak inhibitory activity on the plant pathogen F.culmorum growth (IC(50)=18.8-37.7 uM) (PubMed:27578329). Expressed by the venom gland. Has the structural arrangement of two alpha-helices stabilized by disulfide bonds (CSalpha/alpha 2(S-S)). The two disulfide isomers globular (C1-C3, C2-C4) and beads (C1-C2, C3-C4) do not show activity on Kv10.1/KCNH1/EAG1. Kappa-KTx 1.1 has no activity on Kv1.1/KCNA1 (Kd>>150 uM), Kv1.4/KCNA4, Kv1.5/KCNA5, shaker IR, Kv2.1/KCNB1, Kv3.1/KCNC1, Kv4.2/KCND2, and Kv11.1/KCNH2/ERG1 (PubMed:12034709, PubMed:23726856). Kappa-KTx 1.1 is not able to inhibit the growth of C.albicans, S.cerevisiae or F.oxysporum (PubMed:27578329). Kappa-KTx 1.2 has no activity on Kv10.1/KCNH1/EAG1 (PubMed:27578329). Belongs to the short scorpion toxin superfamily. Potassium channel inhibitor kappa-KTx family. Kappa-KTx 1 subfamily.