Calzada, Maria J. and Annis, Douglas S. and Zeng, Bixi and Marcinkiewicz, Cezary and Banas, Bernhard and Lawler, Jack and Mosher, Deane F. and Roberts, David D. (2004) Identification of novel beta1 integrin binding sites in the type 1 and type 2 repeats of thrombospondin-1. The Journal of biological chemistry 279 (40), pp. 41734-41743.
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Other URL: http://dx.doi.org/10.1074/jbc.M406267200
In addition to the three known beta(1) integrin recognition sites in the N-module of thrombospondin-1 (TSP1), we found that beta(1) integrins mediate cell adhesion to the type 1 and type 2 repeats. The type 1 repeats of TSP1 differ from typical integrin ligands in that recognition is pan-beta(1)-specific. Adhesion of cells that express one dominant beta(1) integrin on immobilized type 1 repeats is specifically inhibited by antagonists of that integrin, whereas adhesion of cells that express several beta(1) integrins is partially inhibited by each alpha-subunit-specific antagonist and completely inhibited by combining the antagonists. beta(1) integrins recognize both the second and third type 1 repeats, and each type 1 repeat shows pan-beta(1) specificity and divalent cation dependence for promoting cell adhesion. Adhesion to the type 2 repeats is less sensitive to alpha-subunit antagonists, but a beta(1) blocking antibody and two disintegrins inhibit adhesion to immobilized type 2 repeats. beta(1) integrin expression is necessary for cell adhesion to the type 1 or type 2 repeats, and beta(1) integrins bind in a divalent cation-dependent manner to a type 1 repeat affinity column. The widely used TSP1 function blocking antibody A4.1 binds to a site in the third type 2 repeat. A4.1 proximally inhibits beta(1) integrin-dependent adhesion to the type 2 repeats and indirectly inhibits integrin-dependent adhesion mediated by the TSP1 type 1 repeats. Although antibody A4.1 is also an antagonist of CD36 binding to TSP1, these data suggest that some biological activities of A4.1 result from antagonism of these novel beta(1) integrin binding sites.
|Date:||1 October 2004|
|Institutions:||Medicine > Lehrstuhl für Innere Medizin II|
|Subjects:||600 Technology > 610 Medical sciences Medicine|
|Refereed:||Yes, this version has been refereed|
|Created at the University of Regensburg:||Yes|
|Deposited On:||15 Mar 2007|
|Last Modified:||20 Jul 2011 20:53|