Type I collagen is a member of group I collagen (fibrillar forming collagen). Trimers of one alpha 2(I) and two alpha 1(I) chains. Expressed in bones. Prolines at the third position of the tripeptide repeating unit (G-X-Y) are hydroxylated in some or all of the chains. These protein fragments were extracted from an ancient rib bone collected at Bariloche in Argentina and estimated to be around 19050 years old. Belongs to the fibrillar collagen family.