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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
General
Ca+2 binding protein
glycoprotein
secreted protein
Properties
SIZE: entity length = 303 aa
MW = 35 kD
COMPARTMENT: extracellular compartment
MOTIF: signal sequence {1-17}
acidic region {22-69}
MOTIF: acidic residue (SEVERAL)
Follistatin-like {71-93}
MOTIF: cysteine residue {C72}
MODIFICATION: cysteine residue {C83}
cysteine residue {C77}
MODIFICATION: cysteine residue {C93}
cysteine residue {C83}
MODIFICATION: cysteine residue {C72}
Kazal-type serine protease inhibitor domain {89-151}
MOTIF: cysteine residue {X+0}
MODIFICATION: cysteine residue {X+X4}
cysteine residue {X+X1}
MODIFICATION: cysteine residue {X+X3}
cysteine residue {X+X2}
MODIFICATION: cysteine residue {X+X5}
cysteine residue {X+X3}
MODIFICATION: cysteine residue {X+X1}
cysteine residue {X+X4}
MODIFICATION: cysteine residue {X+0}
cysteine residue {X+X5}
MODIFICATION: cysteine residue {X+X2}
cysteine residue {C93}
MODIFICATION: cysteine residue {C77}
cysteine residue {C95}
MODIFICATION: cysteine residue {C130}
cysteine residue {C101}
MODIFICATION: cysteine residue {C123}
cysteine residue {C112}
MODIFICATION: cysteine residue {C149}
N-glycosylation site {N116}
cysteine residue {C123}
MODIFICATION: cysteine residue {C101}
cysteine residue {C130}
MODIFICATION: cysteine residue {C95}
cysteine residue {C149}
MODIFICATION: cysteine residue {C112}
FOR-BINDING-OF: serine protease
cysteine residue {C155}
MODIFICATION: cysteine residue {C265}
EF hand
SITE: 261-296
MOTIF: cysteine residue {C265}
MODIFICATION: cysteine residue {C155}
cysteine residue {C273}
MODIFICATION: cysteine residue {C289}
Ca+2-binding site
SITE: 274-285
cysteine residue {C289}
MODIFICATION: cysteine residue {C273}
Database Correlations
OMIM 182120
UniProt P09486
PFAM correlations
Entrez Gene 6678
Kegg hsa:6678
References
- UniProt :accession P09486
- Wikipedia; Note: osteonectin entry
http://en.wikipedia.org/wiki/osteonectin
- Lane TF & Sage EH
The biology of SPARC, a protein that modulates cell-matrix
interactions.
FASEB J 8:163 1994
PMID: 8119487