Inhibits high-voltage activated calcium channels. Shifts the voltage-dependence for activation towards hyperpolarized membrane potentials for L- (Cav1), P/Q- (Cav2.1/CACNA1A) and R-type (Cav2.3/CACNA1E) calcium currents. Causes immediate agitation and clockwise gyration, followed by the gradual development of general flaccid paralysis when injected intracerebroventricular into mice at dose levels of 5 ug per mouse. Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. Belongs to the neurotoxin 02 (plectoxin) family.