2 POLYPEPTIDE TOXINS WITH OPPOSITE EFFECTS ON CALCIUM-UPTAKE IN BOVINE CHROMAFFIN CELLS - ISOLATION FROM THE VENOM OF THE MARINE SNAIL CONUS-DISTANS

Two polypeptide toxins which modulate the uptake of Ca-45(2+) in bovin e chromaffin cells were isolated from the venom of the marine snail Co nus distans. The molecular weights were estimated by gel electrophores is and gel filtration to be 25.5 and 24 kDa, respectively. The purifie d proteins were electrophoretically homogeneous. The 25.5 kDa-componen t caused a concentration-dependent increase of the initial rate of Ca- 45(2+) uptake, but it had no effect on the stimulation evoked uptake. The 24 kDa-component produced the opposite effects; it caused a concen tration-dependent inhibition of the stimulation evoked Ca-45(2+) uptak e, but it did not affect the initial rate. Copyright (C) 1996 Elsevier Science Ltd.