SPARC; basement-membrane protein 40; BM-40; osteonectin; ON; secreted protein acidic & rich in cysteine (SPARC, ON)

Function

• regulates adhesion of osteoblasts & platelets to extracellular matrix
• appears to regulate cell growth through interactions with the extracellular matrix & cytokines
• binds Ca+2 & copper, several types of collagen, albumin, thrombospondin, PDGF & cell membranes
• there are two Ca+2 binding sites; an acidic domain that binds 5 to 8 Ca+2 with a low affinity & an EF-hand loop that binds a Ca+2 ion with a high affinity

Structure

• belongs to the SPARC family
• contains 1 EF-hand domain
• contains 1 follistatin-like domain
• contains 1 Kazal-like domain

Compartment

• secreted, extracellular space, extracellular matrix
• in or around the basement membrane

Expression

• expressed at high levels in tissues undergoing morphogenesis, remodeling & wound repair

More general terms

• glycoprotein
• Ca+2 binding protein
• secreted protein

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=6678
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:6678
• OMIM: https://mirror.omim.org/entry/182120
• UniProt: http://www.uniprot.org/uniprot/P09486.html