This toxin only weakly stabilizes ryanodine receptor 1 (RyR1) opening in a long-lasting subconductance state (55% of the full conductance state obtained only at high concentrations (1 uM)) (PubMed:27114612). In addition, it has been shown to dose-dependently stimulate ryanodine binding to RyR1 with the lowest activity of all calcins (EC(50)=376 nM) (PubMed:27114612). It also augments the bell-shaped calcium-[3H]ryanodine binding curve that is maximal at about 10 uM calcium concentration (PubMed:27114612). It binds a different site as ryanodine (By similarity). It acts synergistically with caffeine (By similarity). In contrast to other calcins, it does not trigger calcium release from sarcoplasmic vesicles even at high concentration (1 uM) (PubMed:27114612). In vivo, intracerebroventricular injection into mice induces neurotoxic symptoms, followed by death (By similarity). Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. Belongs to the scorpion calcin family.