A heterotrimer with 2 α1(I) and 1 α2(I) chains.
Major structural protein of bone, tendons, ligaments, dentin and skin.
Consists of two alpha-1 chains encoded by COL1A1 and one alpha-2 chain encoded by COL1A2 that fold into a triple helix.
Both α chains have repeats of tripeptide composed of glycine and two other amino acids most often proline and hydroxyproline.
Mutations in type I collagen can be sporadic or autosomal dominant.
More than 800 distinct nutations in either COL1A1 or COL1A2 have been reported.