ITGA3 is an integrin alpha subunit. It makes up half of the α3β1 integrin duplex. ITGA3 encodes the integrin alpha 3 chain. Integrins are heterodimeric integral membrane proteins composed of an alpha chain and a beta chain. Alpha chain 3 undergoes post-translational cleavage in the extracellular domain to yield disulfide-linked light and heavy chains that join with beta 1 to form an integrin that interacts with many extracellular-matrix proteins.

The alpha 3 beta 1 integrin is known variously as: very late (activation) antigen 3 ('VLA-3'), very common antigen 2 ('VCA-2'), extracellular matrix receptor 1 ('ECMR1'), and galactoprotein b3 ('GAPB3').