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Structure of a novel extracellular Ca(2+)-binding module in BM-40
E Hohenester1, P Maurer, C Hohenadl
1Department of Structural Biology, University of Basel, Switzerland.
Nature Structural Biology
|January 1, 1996
Summary
This study reveals the crystal structure of the EF-hand pair in human BM-40 (SPARC), an extracellular matrix protein. Unusual structural features and interactions define a novel protein module found in other extracellular proteins.
Area of Science:
- Biochemistry
- Structural Biology
- Extracellular Matrix Biology
Background:
- EF-hand motifs are crucial calcium-binding sites in cytosolic proteins.
- Human BM-40 (SPARC) is an extracellular matrix protein with a known EF-hand pair.
Purpose of the Study:
- To determine the crystal structure of the carboxy-terminal domain of human BM-40 (SPARC).
- To elucidate the structural details and interactions of the EF-hand pair within this extracellular protein.
Main Methods:
- X-ray crystallography at 2.0 A resolution.
Main Results:
- The crystal structure of the human BM-40 (SPARC) carboxy-terminal domain was determined.
- Unusual structural adaptations were observed in both EF-hands, including a cis-peptide bond and a peptide carbonyl ligand in the first, and a disulfide bond stabilizing the second.
- The EF-hand pair forms a tight complex with an amphiphilic amino-terminal helix.
Conclusions:
- The study defines a novel protein module comprising the EF-hand pair and associated helix.
- This module is present in other extracellular proteins, suggesting conserved functions.
- The findings provide insights into calcium-binding and protein interactions in the extracellular matrix.