This gene encodes the alpha-2 subunit of the type IV collagens, an essential component of basement membranes. The encoded protein forms a triple helical heterotrimer comprised of alpha-1 and alpha-2 subunits that assembles into a type IV collagen network. Canstatin, a peptide derived fom the C-terminus of the collagen chain, is a matrikine that has been shown to inhibit angiogenesis. Homozygous knockout mice for this gene exhibit impaired basement membrane integrity and embryonic lethality. This gene shares a bi-directional promoter with a related gene on chromosome 8. [provided by RefSeq, Nov 2015]