Complex sentence: Cobatoxin is a toxin, present in the venom of the Centruroides noxius scorpion, that blocks two K +-channel subtypes; voltage-gated and Ca2 +-activated channels.
Split into simpler sentences: Cobatoxin is a toxin present in the venom of the scorpion "Centruroides noxius". It blocks two potassium channel subtypes; voltage-gated and calcium-activated channels.