... 2002 A single charged surface residue modifies the activity of ikitoxin, a beta-type Na+ channel toxin from Parabuthus transvaalicus A. Bora Inceoglu1,*, Yuki Hayashida2, Jozsef Lango3, Andrew ... Laboratory, University of California, Davis, CA, USAWe previously purified and characterized a peptide toxin, birtoxin, from the South African scorpion Parabuthus transvaalicus. Birtoxin is a 58 -residue, ... grant EY08120 (to ATI) and NEI CoreGrant P30 EY12576. A. B. Inceoglu is partially funded by AnkaraUniversity. Y. Hayashida and A. T. Ishida thank Dr B. Mulloney foruse of the voltage-clamp amplifier...