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Mol. Cells 2010; 30(3): 227-234

Published online September 30, 2010

https://doi.org/10.1007/s10059-010-0111-2

© The Korean Society for Molecular and Cellular Biology

Characterization of the Residues of αX I-Domain and ICAM-1 Mediating Their Interactions

Jeongsuk Choi, Jeasun Choi, and Sang-Uk Nham*

Divisions of Science Education and Biology, Kangwon National University, Chuncheon 200-701, Korea

Correspondence to : *Correspondence: sunham@kangwon.ac.kr

Received: March 19, 2010; Revised: May 19, 2010; Accepted: May 27, 2010

Abstract

Integrin αXβ2 performs a significant role in leukocyte functions including phagocytosis and migration, and binds to a variety of ligands, including fibrinogen, iC3b, and ICAM-1. A particular domain of the α subunit of the integrin - the αX I-domain - is a ligand binding site, and the interaction of the αX I-domain and ICAM-1 on the endothelium is an important step in leukocyte extravasation. In order to elucidate the structural aspects of this interaction, we defined the moieties of the αX and ICAM-1 relevant to their interaction in this study. It was determined that the ICAM-1 binding sites of the αX I-domain were located in the α3α4, βDα5, and βFα7 loops at the top surface of the I-domain. The residues Q202, K242, K243, E298 and D299 on these loops were crucial for the recognition of ICAM-1. Among these residues, K242 and K243 on the βDα5 loop were found to be the most salient, thereby suggesting an ionic interaction between these proteins. Domain 3 of ICAM-1 was identified as a primary binding site for the αX I-domain. Two regions of domain 3 (D229QRLNPTV and E254DEGTQRL) perform critical functions in the binding of the αX I-domain. Especially, the residue E254DEG, is most important with regard to the αX I-domain.

Keywords αXβ2, binding, ICAM-1, I-domain, integrin

Article

Research Article

Mol. Cells 2010; 30(3): 227-234

Published online September 30, 2010 https://doi.org/10.1007/s10059-010-0111-2

Copyright © The Korean Society for Molecular and Cellular Biology.

Characterization of the Residues of αX I-Domain and ICAM-1 Mediating Their Interactions

Jeongsuk Choi, Jeasun Choi, and Sang-Uk Nham*

Divisions of Science Education and Biology, Kangwon National University, Chuncheon 200-701, Korea

Correspondence to:*Correspondence: sunham@kangwon.ac.kr

Received: March 19, 2010; Revised: May 19, 2010; Accepted: May 27, 2010

Abstract

Integrin αXβ2 performs a significant role in leukocyte functions including phagocytosis and migration, and binds to a variety of ligands, including fibrinogen, iC3b, and ICAM-1. A particular domain of the α subunit of the integrin - the αX I-domain - is a ligand binding site, and the interaction of the αX I-domain and ICAM-1 on the endothelium is an important step in leukocyte extravasation. In order to elucidate the structural aspects of this interaction, we defined the moieties of the αX and ICAM-1 relevant to their interaction in this study. It was determined that the ICAM-1 binding sites of the αX I-domain were located in the α3α4, βDα5, and βFα7 loops at the top surface of the I-domain. The residues Q202, K242, K243, E298 and D299 on these loops were crucial for the recognition of ICAM-1. Among these residues, K242 and K243 on the βDα5 loop were found to be the most salient, thereby suggesting an ionic interaction between these proteins. Domain 3 of ICAM-1 was identified as a primary binding site for the αX I-domain. Two regions of domain 3 (D229QRLNPTV and E254DEGTQRL) perform critical functions in the binding of the αX I-domain. Especially, the residue E254DEG, is most important with regard to the αX I-domain.

Keywords: αXβ2, binding, ICAM-1, I-domain, integrin

Mol. Cells
Nov 30, 2022 Vol.45 No.11, pp. 763~867
COVER PICTURE
Naive (cyan) and axotomized (magenta) retinal ganglion cell axons in Xenopus tropicalis (Choi et al., pp. 846-854).

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