Vascular adhesion protein 1 (VAP-1), also known as AOC3 (amine oxidase copper-containing 3) or SSAO (semicarbazide-sensitive amine oxidase) is a 170kD type II transmembrane glycoprotein consisting of two disulfide-linked 763aa subunits. It is expressed on endothelium, vascular smooth muscle, and adipocytes. The extracellular domain mediates lymphocyte rolling, adhesion, possibly extravasations during inflammation, and possesses monoamine oxidase activity. Adipocytes can release a soluble form via metalloproteinase cleavage. Human VAP-1 ECD shares 83% and 88% aa sequence identity with mouse and canine VAP-1 ECD, respectively.