Alignment of VEGF sequences. Owing to the diversification of this toxin family, classification of venom VEGFs is difficult. Ovophis VEGF 1 [AB852007] possesses a 24-residue insert seen in no other sequence. Ovophis VEGF 5 [AB848274] and Protobothrops VEGF 1 [AB848141] are homologous to vammin, from the venom of Vipera ammodytes. All three of these display short C-terminal extensions of 16-17 residues that bind heparin . Both vammin and VR-1, a VEGF from Daboia russellii venom, enhance vascular permeability with great potency. Another subclass of VEGF including Ovophis VEGF 3-4 [AB852009, AB852010] and Protobothrops VEGF 3 [AB851941] comprise a subclass with no C-terminal extension, or an extremely short extension corresponding to the C-terminus of Ovophis VEGF 1-2 [AB852007, AB852008] and Protobothrops VEGF 2 [AB851940]. These are significantly shorter than barietin, from the venom of Bitis arietans, and they do not align well with it or with vammin.