|PROSITE documentation PDOC00453|
Somatomedin B, a serum factor of unknown function, is a cysteine-rich 44 residues peptide which is proteolytically derived from the N-terminal extremity of the cell-substrate adhesion protein vitronectin . Somatomedin B-like (SMB) domains are also found [2,3] in the following proteins:
The SMB domain of vitronectin has been demonstrated to interact with both the urokinase receptor and the plasminogen activator inhibitor-1 (PAI-1) and the conserved cysteines of the NPP1 somatomedin B-like domain have been shown to mediate homodimerization .
As shown in the following schematic representation below the SMB domain contains eight Cys residues, arranged into four disulfide bonds. It has been suggested that the active SMB domain may be permitted considerable disulfide bond heterogeneity or variability, provided that the Cys25-Cys31 disulfide bond is preserved. The three dimensional structure of the SMB domain is extremely compact and the disulfide bonds are packed in the center of the domain forming a covalently bonded core . The structure of the SMB domain presents a new protein fold, with the only ordered secondary structure being a single-turn α-helix and a single-turn 3(10)-helix (see <PDB:1OC0>) .
'C': conserved cysteine probably involved in a disulfide bond. '*': position of the pattern.
The profile we developed covers the entire SMB domain.Expert(s) to contact by email:
December 2004 / Pattern and text revised.
PROSITE methods (with tools and information) covered by this documentation:
|1||Authors||Jenne D. Stanley K.K.|
|Title||Nucleotide sequence and organization of the human S-protein gene: repeating peptide motifs in the 'pexin' family and a model for their evolution.|
|Title||Homology of placental protein 11 and pea seed albumin 2 with vitronectin.|
|Source||Biochem. Biophys. Res. Commun. 176:1000-1006(1991).|
|3||Authors||Gijsbers R. Ceulemans H. Bollen M.|
|Title||Functional characterization of the non-catalytic ectodomains of the nucleotide pyrophosphatase/phosphodiesterase NPP1.|
|Source||Biochem. J. 371:321-330(2003).|
|4||Authors||Kamikubo Y. De Guzman R. Kroon G. Curriden S. Neels J.G. Churchill M.J. Dawson P. Oldziej S. Jagielska A. Scheraga H.A. Loskutoff D.J. Dyson H.J.|
|Title||Disulfide bonding arrangements in active forms of the somatomedin B domain of human vitronectin.|
|5||Authors||Zhou A. Huntington J.A. Pannu N.S. Carrell R.W. Read R.J.|
|Title||How vitronectin binds PAI-1 to modulate fibrinolysis and cell migration.|
|Source||Nat. Struct. Biol. 10:541-544(2003).|