Identification of the cartilage α 1(XI) chain in type V collagen from bovine bone

Type V collagen prepared from bovine bone was resolved into three distinct α-chains by high performance liquid chromatography and gel electrophoresis. Peptide mapping established two chains as α 1(V) and α 2(V) as expected and the third as the cartilage α 1(XI) chain (previously thought to be unique to cartilage). In adult bone, the type V collagen fraction was richer in α 1(XI) chains than in fetal bone (about 1/3 of the chains in the adult). How these polypeptides are organized into native molecules is not yet clear, though the stoichiometry suggests cross-type heterotrimers between the type V and XI chains.