The Loxtox protein family in Loxosceles intermedia (Mello-Leitão) venom.

We isolated cDNA sequences coding for dermonecrotic/sphingomyelinases factor proteins from the brown spider Loxosceles intermedia, here named Loxtox proteins. The amino acid sequences based on cloned cDNA of several Loxtox proteins revealed at least six distinct groups of proteins expressed in the venom gland. The level of similarity among the toxins varied from 99% to 55%. The finding of several isoforms of Loxtox in the venom of this spider may reflect an evolutionary adaptation for different prey types and reinforces the idea of an efficient mutational mechanism in the venom gland of spiders.