This toxin stabilizes ryanodine receptor 1 (RyR1) opening in a long-lasting subconductance state (40% of the full conductance state) (PubMed:27114612). Furthermore, it triggers calcium release from sarcoplasmic vesicles (64.2 nM are enough to induce a sharp release, and 50% of the total calcium is released after toxin (100 nM) addition) probably by acting as a cell-penetrating peptide (CPP) (PubMed:27114612). In addition, it has been shown to dose-dependently stimulate ryanodine binding to RyR1 (EC(50)=3.2 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 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.