This gene encodes the alpha chain of type XVIII collagen. This collagen is one of the multiplexins, extracellular matrix proteins that contain multiple triple-helix domains (collagenous domains) interrupted by non-collagenous domains. The proteolytically produced C-terminal fragment of type XVIII collagen is endostatin, a potent antiangiogenic protein. Mutations in this gene are associated with Knobloch syndrome. The main features of this syndrome involve retinal abnormalities so type XVIII collagen may play an important role in retinal structure and in neural tube closure. Two transcript variants encoding different isoforms have been found for this gene.
Present in multiple organs with highest levels in liver, lung and kidney.
翻译后修饰
Prolines at the third position of the tripeptide repeating unit (G-X-Y) are hydroxylated in some or all of the chains.
疾病
Defects in COL18A1 are a cause of Knobloch syndrome (KNO) [MIM:267750]. KNO is an autosomal recessive disorder defined by the occurrence of high myopia, vitreoretinal degeneration with retinal detachment, macular abnormalities and occipital encephalocele.
相似性
Belongs to the multiplexin collagen family.
Contains 1 FZ (frizzled) domain.
Contains 1 TSP N-terminal (TSPN) domain.
功能
COLA18A probably plays a major role in determining the retinal structure as well as in the closure of the neural tube.
Endostatin potently inhibits endothelial cell proliferation and angiogenesis. May inhibit angiogenesis by binding to the heparan sulfate proteoglycans involved in growth factor signaling.