Ev37 selectively inhibits Kv1.3/KCNA3 channel (IC(50)=0.95 uM). Both N-terminal and C-terminal domains are likely involved in the interaction with Kv1.3, since neither Ev37-N (1-36) nor Ev37-C (37-78) block Kv1.3 channel. Expressed by the venom gland. Does not block Kv1.1/KCNA1 and Kv1.2/KCNA2 channels. Neither the full-length Ev37 nor the two individual domains (Ev37-N (1-36) and Ev37-C (37-78)) show any cytolytic effects on bacteria or on red blood cells. Belongs to the long chain scorpion toxin family. Class 3 subfamily.