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cartilage oligomeric matrix protein; thrombospondin 5 (COMP, EDM1, PSACH, TSP5)

Function: - may play a role in the structural integrity of cartilage via its interaction with other extracellular matrix proteins such as the collagens & fibronectin - can mediate the interaction of chondrocytes with the cartilage extracellular matrix through interaction with cell surface integrin receptors - could play a role in the pathogenesis of osteoarthritis - potent suppressor of apoptosis in both primary chondrocytes & transformed cells - suppresses apoptosis by blocking activation of caspase-3 & by inducing the IAP family of survival proteins (BIRC3, BIRC2, BIRC5 & XIAP) - essential for maintaining a vascular smooth muscle cells contractile/differentiated phenotype under physiological & pathological stimuli - maintains this phenotype by interacting with ITGA7 (putative) - exists in a more compact conformation in the presence of Ca+2 & shows a more extended conformation in the absence of Ca+2 - interacts with ITGB3, ITGA5 & FN1 - binding to FN1 requires the presence of divalent cations (Ca+2, Mg+2 or Mn+2) - the greatest amount of binding is seen in the presence of Mn+2 - interacts with MATN1, MATN3, MATN4 & ACAN - binds heparin, heparan sulfate & chondroitin sulfate - EDTA diminishes significantly its binding to ACAN & abolishes its binding to MATN3, MATN4 & chondroitin sulfate - interacts with collagen 1, collagen 2 & collagen 9 - interaction with thesecollagens is dependent on the presence of Zn+2 - interacts with ADAMTS12 - nteracts with ITGA7 (putative) Cofactor: binds 11-14 Ca+2 per subunit Structure: - pentamer; disulfide-linked - the cell attachment motif - mediates attachment to chondrocytes - mediates induction of both the IAP family of survival proteins & the antiapoptotic response - the TSP C-terminal domain mediates interaction with FN1 & ACAN - belongs to the thrombospondin family - contains 4 EGF-like domains - contains 1 TSP C-terminal (TSPC) domain - contains 8 TSP type-3 repeats Compartment: - secreted, extracellular space, extracellular matrix Expression: - abundantly expressed in chondrocyte extracellular matrix - also found in bone, tendon, ligament, synovium & blood vessels - present during the earliest stages of limb maturation & is later found in regions where the joints develop Pathology: - defects are the cause of: a) multiple epiphyseal dysplasia 1 b) pseudoachondroplasia - increased amounts are produced during late stages of osteoarthritis in the area adjacent to the main defect Laboratory: - cartilage oligomeric matrix protein in serum

Related

multiple epiphyseal dysplasia (EDM) pseudoachondroplasia

General

matrix protein oligomerizing protein

Properties

SIZE: entity length = 757 aa MW = 83 kD COMPARTMENT: extracellular matrix MOTIF: signal sequence {1-20} COMP N-terminal {22-86} MOTIF: cysteine residue {C69} MODIFICATION: cysteine residue {CINTERCHAIN (PROBABLE} cysteine residue {C72} MODIFICATION: cysteine residue {CINTERCHAIN (PROBABLE} EGF domain {87-126} MOTIF: cysteine residue {C91} MODIFICATION: cysteine residue {C102} cysteine residue {C96} MODIFICATION: cysteine residue {C111} cysteine residue {C102} MODIFICATION: cysteine residue {C91} cysteine residue {C111} MODIFICATION: cysteine residue {C96} cysteine residue {C114} MODIFICATION: cysteine residue {C125} N-glycosylation site {N121} cysteine residue {C125} MODIFICATION: cysteine residue {C114} EGF domain {127-179} MOTIF: cysteine residue {C131} MODIFICATION: cysteine residue {C142} cysteine residue {C136} MODIFICATION: cysteine residue {C151} cysteine residue {C142} MODIFICATION: cysteine residue {C131} cysteine residue {C151} MODIFICATION: cysteine residue {C136} cysteine residue {C154} MODIFICATION: cysteine residue {C178} cysteine residue {C178} MODIFICATION: cysteine residue {C154} EGF domain {180-222} MOTIF: cysteine residue {C184} MODIFICATION: cysteine residue {C197} cysteine residue {C191} MODIFICATION: cysteine residue {C206} cysteine residue {C197} MODIFICATION: cysteine residue {C184} cysteine residue {C206} MODIFICATION: cysteine residue {C191} cysteine residue {C209} MODIFICATION: cysteine residue {C221} cysteine residue {C221} MODIFICATION: cysteine residue {C209} EGF domain {225-267} MOTIF: cysteine residue {C229} MODIFICATION: cysteine residue {C243} cysteine residue {C237} MODIFICATION: cysteine residue {C253} cysteine residue {C243} MODIFICATION: cysteine residue {C229} cysteine residue {C253} MODIFICATION: cysteine residue {C237} cysteine residue {C255} MODIFICATION: cysteine residue {C266} cysteine residue {C266} MODIFICATION: cysteine residue {C255} TSP {268-300} MOTIF: cysteine residue {C282} MODIFICATION: cysteine residue {C287} cysteine residue {C287} MODIFICATION: cysteine residue {C282} cysteine residue {C292} MODIFICATION: cysteine residue {C312} TSP {301-336} MOTIF: cysteine residue {C312} MODIFICATION: cysteine residue {C292} cysteine residue {C328} MODIFICATION: cysteine residue {C348} TSP {337-359} MOTIF: cysteine residue {C348} MODIFICATION: cysteine residue {C328} cysteine residue {C351} MODIFICATION: cysteine residue {C371} TSP {360-395} MOTIF: Cell attachment site {367-369} cysteine residue {C371} MODIFICATION: cysteine residue {C351} cysteine residue {C387} MODIFICATION: cysteine residue {C407} TSP {396-418} MOTIF: cysteine residue {C407} MODIFICATION: cysteine residue {C387} cysteine residue {C410} MODIFICATION: cysteine residue {C430} TSP {419-456} MOTIF: cysteine residue {C430} MODIFICATION: cysteine residue {C410} cysteine residue {C448} MODIFICATION: cysteine residue {C468} TSP {457-492} MOTIF: cysteine residue {C468} MODIFICATION: cysteine residue {C448} cysteine residue {C484} MODIFICATION: cysteine residue {C504} TSP {493-528} MOTIF: cysteine residue {C504} MODIFICATION: cysteine residue {C484} cysteine residue {C520} MODIFICATION: cysteine residue {C741} Mediates cell survival and induction of the IAP family of survival proteins {527-757} MOTIF: TSP C-terminal {532-746} cysteine residue {C741} MODIFICATION: cysteine residue {C520} N-glycosylation site {N742} SECRETED-BY: chondrocyte

Database Correlations

OMIM correlations MORBIDMAP 600310 UniProt P49747 PFAM correlations Entrez Gene 1311 Kegg hsa:1311

References

  1. OMIM :accession 600310
  2. UniProt :accession P49747
  3. GeneReviews http://www.ncbi.nlm.nih.gov/sites/genetests/lab/gene/COMP