title: COMP (cartilage oligomeric matrix protein) is structurally related to the thrombospondins.
abstract: Cloning and sequence analysis of cartilage oligomeric matrix protein (COMP) cDNA, representing a cartilage pentameric protein, revealed a protein of 755 amino acid residues with a calculated molecular mass of 82,700 Da. Expression of the cDNA in COS cells showed that COMP is a homopolymer composed of five identical disulfide-linked subunits. COMP is homologous to the carboxyl-terminal half of thrombospondin, and the homologies include 89% and 54% of the residues in COMP and thrombospondin, respectively. The similarities are most pronounced in the carboxyl-terminal domains and in the calcium binding type 3 repeat domains in which about 60% of the amino acid residues are identical. In the type 2/epidermal growth factor repeat domains the two proteins contain 41% identical residues. The sequence of the amino-terminal 84-amino acid residues is unique for COMP. Comparison of the amino acid sequences in the type 2 and type 3 repeat domains of COMP and the thrombospondins shows that COMP is the product of a unique gene and not the result of an alternatively spliced thrombospondin gene.
authors.affiliation: Department of Medical and Physiological Chemistry, University of Lund, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Oldberg
authors.forename: P
authors.initials: P
authors.lastname: Antonsson
authors.forename: K
authors.initials: K
authors.lastname: Lindblom
authors.forename: D
authors.initials: D
authors.lastname: Heinegård
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D016326:Extracellular Matrix Proteins; D015870:Gene Expression; D006023:Glycoproteins / Q000737:chemistry / Q000235:genetics*; D064235:Matrilin Proteins; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010980:Platelet Membrane Glycoproteins / Q000737:chemistry; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D016415:Sequence Alignment; D019699:Thrombospondins; D014162:Transfection
chemical_list: D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; D064235:Matrilin Proteins; D010980:Platelet Membrane Glycoproteins; D012333:RNA, Messenger; D019699:Thrombospondins; D004247:DNA