Osteonectin cDNA sequence reveals potential binding regions for calcium and hydroxyapatite and shows homologies with both a basement membrane protein (SPARC) and a serine proteinase inhibitor (ovomucoid).

摘要: Abstract Osteonectin is a prominent noncollagenous protein of developing bone. A 2150-base-pair cDNA coding for osteonectin, isolated from bovine bone cell lambda gt11 expression library, was sequenced and identified by comparison with sequence data. The nucleotide predicts that osteonectin contains 304 amino acids, including 17-residue signal peptide. Analysis the deduced suggests secreted at least four distinct structural domains. An acidic region terminus appears to be potential hydroxyapatite-binding site. This followed second domain, rich in cysteine, shows homology cysteine-rich domains turkey ovomucoid other serine proteinase inhibitors. Two sequences homologous central calcium-binding loops "EF hands" thus having high-affinity sites are located two within carboxyl-terminal half protein. Finally, near identity (greater than 90%) another protein, SPARC (secreted cysteine), mouse parietal endoderm. These data suggest present selected tissues, multifunctional