A peptide originally isolated from the scorpion L. quinquestriatus; blocks BKCas in GH3 rat pituitary tumor cells and primary bovine aortic smooth muscle cells (Kds = 2.1 and ~2.1 nM, respectively); selectively blocks Kv1.2 and Kv1.3 over Kv1.1, Kv1.5, and Kv3.1 (Kds = 14, 2.6, >1,000, >100, >1,000 nM, respectively); blocks human KCa5.1 (Slo3) by 47% at a concentration of 100 nM (pH 7.4); blocks human IKCa1/KCa3.1 (Kd = 10 nM),