Spider venom α-latrotoxin of 1401 aas, α-LTX. It induces massive exocytosis after binding to a surface receptor, latrophilin (LPH). In this process, it first induced membrane depolarization by inhibition of repolarizing K⁺ channels followed by the appearance of Ca²⁺ transients. In a second phase, the toxin induced a large inward current and a prominent increase in intracellular calcium ions, reflecting pore formation (Lajus et al. 2006).