HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 283, Issue 42, 28487-28496, October 17, 2008

This Article Full Text Full Text (PDF) All Versions of this Article: 283/42/28487    most recent M804257200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Schar, C. R. Articles by Peterson, C. B. Search for Related Content PubMed PubMed Citation Articles by Schar, C. R. Articles by Peterson, C. B. Social Bookmarking                      What's this?

Characterization of a Site on PAI-1 That Binds to Vitronectin Outside of the Somatomedin B Domain^*

Christine R. Schar, Jan K. Jensen, Anni Christensen, Grant E. Blouse, Peter A. Andreasen, and Cynthia B. Peterson¹

From the Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996 and the Laboratory of Cellular Protein Science, Department of Molecular and Structural Biology, University of Aarhus, Aarhus, Denmark 8000

Vitronectin and plasminogen activator inhibitor-1 (PAI-1) are proteins that interact in the circulatory system and pericellular region to regulate fibrinolysis, cell adhesion, and migration. The interactions between the two proteins have been attributed primarily to binding of the somatomedin B (SMB) domain, which comprises the N-terminal 44 residues of vitronectin, to the flexible joint region of PAI-1, including residues Arg-103, Met-112, and Gln-125 of PAI-1. A strategy for deletion mutagenesis that removes the SMB domain demonstrates that this mutant form of vitronectin retains PAI-1 binding (Schar, C. R., Blouse, G. E., Minor, K. M., and Peterson, C. B. (2008) J. Biol. Chem. 283, 10297–10309). In the current study, the complementary binding site on PAI-1 was mapped by testing for the ability of a battery of PAI-1 mutants to bind to the engineered vitronectin lacking the SMB domain. This approach identified a second, separate site for interaction between vitronectin and PAI-1. The binding of PAI-1 to this site was defined by a set of mutations in PAI-1 distinct from the mutations that disrupt binding to the SMB domain. Using the mutations in PAI-1 to map the second site suggested interactions between -helices D and E in PAI-1 and a site in vitronectin outside of the SMB domain. The affinity of this second interaction exhibited a K_D value 100-fold higher than that of the PAI-1-somatomedin B interaction. In contrast to the PAI-1-somatomedin B binding, the second interaction had almost the same affinity for active and latent PAI-1. We hypothesize that, together, the two sites form an extended binding area that may promote assembly of higher order vitronectin-PAI-1 complexes.

Received for publication, June 3, 2008

^* This work was supported, in whole or in part, by National Institutes of Health Grant HL50676 from NHLBI (to C. B. P.). This work was also supported by grants from the Danish Cancer Society, the Danish Research Agency, the University of Aarhus, and the European Commission (to P. A. A.) and by a grant from the Carlsberg Foundation (to G. E. B.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ To whom correspondence should be addressed: Dept. of Biochemistry and Cellular and Molecular Biology, M407 Walters Life Sciences Bldg., University of Tennessee, Knoxville, TN 37996. Fax: 865-974-6306; E-mail: cynthia_peterson{at}utk.edu.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?