A novel Kv1.1 potassium channel blocking toxin from the venom of Palamneus gravimanus (Indian black scorpion)

a peptide toxin was isolated from the venom of palamneus gravimanus, the indian black scorpion, to block human kv1.1 channels expressed in xenopus laevis oocytes. a 4.5 kd peptide (toxin), as confirmed by sds-page, was purified to homogeneity by ion exchange chromatography using cm-sephadex c-25 followed by sephadex g-50 gel filtration. palamneus gravimanus toxin (pgt) selectively blocks the human cloned voltage-gated potassium channel hkv1.1 in a two-electrode voltage-clamp (tevc) technique. the results obtained indicate that the toxin blocks the hkv1.1 channel at a nanomolar concentration range (ki value of 10 nm) of the peptide to the external side of the cell. the blockage seems to be voltage-dependent. comparative structure of pgt (a 4.5 kd peptide) with btk-2 suggests a close relationship; therefore this toxin can be employed to investigate the hkv1.1 channel structure.