This toxin activates ryanodine receptors RyR1 and RyR2 by inducing a long-lasting subconductance state (35% of the full conductance stateon RyR1) (PubMed:19389159, PubMed:27114612). Furthermore, it triggers calcium release from sarcoplasmic vesicles (11.8 nM are enough to induce a sharp release on RyR1, and 55% of the total calcium is released after toxin (100 nM) addition on RyR1) probably by acting as a cell-penetrating peptide (CPP) (PubMed:19389159). In addition, it has been shown to dose-dependently stimulate ryanodine binding to RyR1 (EC(50)=14.8 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 (PubMed:19389159). 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.