Collagen Type XI is an 1806 amino acid protein belonging to the fibrillar collagen family. Collagen Type XI is thought to play an important role in fibrillogenesis by controlling lateral growth of collagen II fibrils. This protein forms trimers composed of three different chains: a 1(XI), a 2(XI), and a 3(XI). a 3(XI) is a post-translational modification of a 1(II). a 1(V) can also be found instead of a 3(XI). Collagen Type XI has three named isoforms (A,B,C) and additional isoforms seem to exist, stemming from alternative usage of exon IIA or exon IIB. Transcripts containing exon IIA or IIB are present in cartilage, but exon IIB is preferentially utilized in transcripts from tendon. Collagen Type XI contains a single collagen binding TSP N-terminal (TSPN) domain. Collagen Type XI is expressed in cartilage, placenta and some tumor or virally transformed cell lines. Isoform expression can be tissue specific. Defects in the COL11A gene are the cause of Stickler syndrome type 2 (STL2), or beaded vitreous type, due to the presence of irregularly thickened fiber bundles throughout vitreous cavity.
a1(XI) collagen; chondrodysplasia; COBA1; Collagen alpha 1; Collagen alpha-1(XI) chain; collagen XI, alpha-1 polypeptide; collagen, type XI, alpha 1; pro-alpha1(XI) collagen; procollagen, type XI, alpha 1; STL3; XI chain precursor