DocumentCode :
386541
Title :
Conformational activation of 2 integrins, their I domains, and regulation by small molecule antagonists
Author :
Springer, Timothy A. ; Shimaoka, Motomu ; Lu, Chafen ; Xiao, Tsan ; Carman, Chris ; Salas, Azucena ; Wang, Jia-huai ; Liu, Jin-huan ; Yang, Yuting ; Blacklow, Steve ; Beglova, Natalia ; Takagi, Jun
Volume :
1
fYear :
2002
fDate :
2002
Firstpage :
730
Abstract :
The inserted or I domain of the integrin LFA-1 ( L 2) mediates binding to ligands such as the IgSF member ICAM-1. Mutation has been used to introduce disulfide bonds that lock the L I domain in two distinct conformations termed open and closed. Wild type, resting L 2 requires activation for binding to ICAM-1. Locked closed L 2 is inactive and resistant to activation whereas locked open L 2 is constitutively active. I domains can be expressed in the absence of other integrin domains with artificial membrane anchors. In static adhesion assays, the locked open I domain is adhesive and the locked closed and wild type I domains are not. However, in flow chamber assays, the wild type I domain mediates rolling, whereas the locked open I domain mediates firm adhesion, reflecting how adhesive function in the vasculature is poised to mediate rolling under basal conditions and firm adhesion after activation. Real time ligand binding assays using surface plasmon resonance show that locking open the I domain increases its affinity for ICAM-1 by 9,000 fold, and that its kinetics and KD are comparable to measurements on active, intact L 2. Two classes of small molecule antagonists can be discriminated.
Keywords :
adhesion; biomembranes; blood vessels; cellular biophysics; molecular biophysics; molecular configurations; proteins; surface plasmon resonance; I domains; ICAM-1; IgSF member; adhesive function; artificial membrane anchors; basal conditions; binding; closed conformation; conformational activation; disulfide bonds; firm adhesion; flow chamber assays; inserted domain; integrin LFA-1; ligands; locked closed L 2; locked open L 2; mutation; open conformation; real time ligand binding assays; regulation; rolling; small molecule antagonists; static adhesion assays; surface plasmon resonance; vasculature; wild type resting L 2; Adhesives; Biomembranes; Genetic mutations; Inhibitors; Inspection; Kinetic theory; Nuclear magnetic resonance; Plasmons;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Engineering in Medicine and Biology, 2002. 24th Annual Conference and the Annual Fall Meeting of the Biomedical Engineering Society EMBS/BMES Conference, 2002. Proceedings of the Second Joint
ISSN :
1094-687X
Print_ISBN :
0-7803-7612-9
Type :
conf
DOI :
10.1109/IEMBS.2002.1137041
Filename :
1137041
Link To Document :
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