PMID: 9233787

 

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Title : Crystal structure of a pair of follistatin-like and EF-hand calcium-binding domains in BM-40

Abstract :

1. BM-40 (also known as SPARC or osteonectin ) is an anti-adhesive secreted glycoprotein involved in tissue remodelling
2. Apart from an acidic N-terminal segment, BM-40 consists of a follistatin-like (FS) domain and an EF-hand calcium-binding (EC) domain
3. Here we report the crystal structure at 3 .1 A resolution of the FS-EC domain pair of human BM-40
4. The two distinct domains interact through a small interface that involves the EF-hand pair of the EC domain
5. Residues implicated in cell binding, inhibition of cell spreading and disassembly of focal adhesions cluster on one face of BM-40 , opposite the binding epitope for collagens and the N-linked carbohydrate
6. The elongated FS domain is structurally related to serine protease inhibitors of the Kazal family
7. Notable differences are an insertion into the inhibitory loop in BM-40 and a protruding N-terminal beta-hairpin with striking similarities to epidermal growth factor
8. This hairpin is likely to act as a rigid spacer in proteins containing tandemly repeated FS domains , such as follistatin and agrin , and forms the heparin-binding site in follistatin