A NOVEL PEPTIDE FROM FUNNEL-WEB SPIDER VENOM, OMEGA-AGA-TK, SELECTIVELY BLOCKS P-TYPE CALCIUM CHANNELS

In the course of purification of ω-Aga-IVA, a specific P-type calcium channel blocker, from the venom of Agelenopsis aperta we discovered a novel peptide. This peptide, named ω-agatoxin Tsukuba (ω-Aga-TK), also blocked P-type channels and was twelve times more abundant in the venom than ω-Aga-IVA. ω-Aga-TK was purified to homogeneity by a two-step reverse-phase HPLC procedure. Its amino acid sequence is 71% identical to that of ω-Aga-IVA. ω-Aga-TK has a negatively charged N-terminus, whereas α-Aga-IVAA has a positively charged one. Electrophysiological data indicate that ω-Aga-TK is a potent and selective inhibitor of P-type channels. © 1993 Academic Press, Inc.