Structural highlights
Function
[SPRC_HUMAN] Appears to regulate cell growth through interactions with the extracellular matrix and cytokines. Binds calcium and copper, several types of collagen, albumin, thrombospondin, PDGF and cell membranes. There are two calcium binding sites; an acidic domain that binds 5 to 8 Ca(2+) with a low affinity and an EF-hand loop that binds a Ca(2+) ion with a high affinity.
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
The EF-hand is a highly conserved Ca(2+)-binding motif found in many cytosolic Ca(2+)-modulated proteins. Here we report the crystal structure at 2.0 A resolution of the carboxy-terminal domain of human BM-40 (SPARC, osteonectin), an extracellular matrix protein containing an EF-hand pair. The two EF-hands interact canonically but their detailed structures are unusual. In the first EF-hand a one-residue insertion is accommodated by a cis-peptide bond and by substituting a carboxylate by a peptide carbonyl as a Ca2+ ligand. The second EF-hand is stabilized by a disulphide bond. The EF-hand pair interacts tightly with an amphiphilic amino-terminal helix, reminiscent of target peptide binding by calmodulin. The present structure defines a novel protein module occurring in several other extracellular proteins.
Structure of a novel extracellular Ca(2+)-binding module in BM-40.,Hohenester E, Maurer P, Hohenadl C, Timpl R, Jansonius JN, Engel J Nat Struct Biol. 1996 Jan;3(1):67-73. PMID:8548457[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Hohenester E, Maurer P, Hohenadl C, Timpl R, Jansonius JN, Engel J. Structure of a novel extracellular Ca(2+)-binding module in BM-40. Nat Struct Biol. 1996 Jan;3(1):67-73. PMID:8548457
