Potently inhibits adhesion of alpha-4/beta-1 (ITGA4/ITGB1) and alpha-9/beta-1 (ITGA9/ITGB1) integrins to VCAM1, and adhesion of alpha-5/beta-1 (ITGA5/ITGB1) integrin to fibronectin. Has a much less effect on alpha-IIb/beta-3 (ITGA2B/ITGB3) integrin. Also potently inhibits neutrophil migration across TNF-alpha-activated human umbilical endothelial cells. Heterodimer with subunit beta; disulfide-linked. Expressed by the venom gland. Belongs to the disintegrin family. Dimeric disintegrin subfamily.