Collagen Type V: A fibrillar collagen found widely distributed as a minor component in tissues that contain COLLAGEN TYPE I and COLLAGEN TYPE III. It is a heterotrimeric molecule composed of alpha1(V), alpha2(V) and alpha3(V) subunits. Several forms of collagen type V exist depending upon the composition of the subunits that form the trimer.Collagen: A polypeptide substance comprising about one third of the total protein in mammalian organisms. It is the main constituent of SKIN; CONNECTIVE TISSUE; and the organic substance of bones (BONE AND BONES) and teeth (TOOTH).Collagen Type I: The most common form of fibrillar collagen. It is a major constituent of bone (BONE AND BONES) and SKIN and consists of a heterotrimer of two alpha1(I) and one alpha2(I) chains.Collagen Type III: A fibrillar collagen consisting of three identical alpha1(III) chains that is widely distributed in many tissues containing COLLAGEN TYPE I. It is particularly abundant in BLOOD VESSELS and may play a role in tissues with elastic characteristics.