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Coiled coil region of thrombospondin-5 (TSP-5) This family contains the N-terminal coiled coil region of TSP-5, also known as cartilage oligomeric matrix protein (COMP). It forms a pentameric left-handed coiled coil (COMPcc) with a channel that is a unique carrier for lipophilic compounds. It is known to bind hydrophilic signaling molecules such as vitamin D3 and vitamin A, making it a possible targeted drug delivery system. TSP-5/COMP is expressed in all types of cartilage as well as in the vitreous of the eye, tendons, vascular smooth muscle cells, and heart. The pentamer is stabilized by inter-subunit disulfide bonds formed between cysteine residues adjacent to the C-terminal end of the coiled coil region. TSP-5 is essential for modulating the phenotypic transition of vascular smooth muscle cells and vascular remodeling. Mutations in TSP-5 result in two different inherited chondrodysplasias and osteoarthritic phenotypes: pseudoachondroplasia and multiple epithelial dysplasia. Deficiency of TSP-5 causes dilated cardiomyopathy (DCM), a common cause of congestive heart failure. Early increase in serum TSP-5 is associated with joint damage progression in patients with rheumatoid arthritis, thus representing a novel indicator of an activated destructive process in the joint. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",