FUNCTION Type I collagen is a member of group I collagen (fibrillar forming collagen).SUBUNIT Trimers of one alpha 2(I) and two alpha 1(I) chains. Interacts with MRC2 (By similarity). Interacts with TRAM2 (PubMed:14749390). Interacts with MFAP4 in a Ca (2+)-dependent manner (By similarity).INTERACTION Forms the fibrils of tendon, ligaments and bones. In bones the fibrils are mineralized with calcium hydroxyapatite.DOMAIN The C-terminal propeptide, also known as COLFI domain, have crucial roles in tissue growth and repair by controlling both the intracellular assembly of procollagen molecules and the extracellular assembly of collagen fibrils. It binds a calcium ion which is essential for its function (By similarity).PTM Contains mostly 4-hydroxyproline. Proline residues at the third position of the tripeptide repeating unit (G-X-Y) are hydroxylated in some or all of the chains.PTM Contains 3-hydroxyproline at a few sites. This modification occurs on the first proline residue in the sequence motif Gly-Pro-Hyp, where Hyp is 4-hydroxyproline.PTM Lysine residues at the third position of the tripeptide repeating unit (G-X-Y) are 5-hydroxylated in some or all of the chains.PTM O-glycosylated on hydroxylated lysine residues. The O-linked glycan consists of a Glc-Gal disaccharide.DISEASE The disease is caused by variants affecting the gene represented in this entry.DISEASE The disease may be caused by variants affecting the gene represented in this entry.DISEASE The disease is caused by variants affecting the gene represented in this entry.DISEASE The disease is caused by variants affecting the gene represented in this entry.DISEASE The disease is caused by variants affecting the gene represented in this entry.DISEASE The disease is caused by variants affecting the gene represented in this entry.DISEASE The disease is caused by variants affecting the gene represented in this entry.DISEASE The disease is caused by variants affecting the gene represented in this entry.DISEASE Disease susceptibility is associated with variants affecting the gene represented in this entry.DISEASE A chromosomal aberration involving COL1A1 is found in dermatofibrosarcoma protuberans. Translocation t(17;22)(q22;q13) with PDGF.SIMILARITY Belongs to the fibrillar collagen family.SEQUENCE CAUTION Extended N-terminus.ONLINE INFORMATION The COL1A1 gene homepageONLINE INFORMATION Type-I collagen entry