Purified by immunoaffinity chromatography. The collagens are a superfamily of proteins that play a role in maintaining the integrity of various tissues. Collagens are extracellular matrix proteins and have a triple helical domain as their common structural element. Collagen VI is a major structural component of microfibrils. The basic structural unit of collagen VI is a heterotrimer of the alpha 1(VI), alpha 2(VI), and alpha 3(VI) chains. Mutations in the genes that code for the collagen VI subunits result in the autosomal dominant disorder, Bethlem myopathy. Source: Collagen Type VI, from human placenta.