Work

Association of the Membrane Proximal Regions of the α and β Subunit Cytoplasmic Domains Constrains an Integrin in the Inactive State

Year: 2001

Type: article

Abstract: The adhesiveness of integrins is regulated through a process termed "inside-out" signaling. To understand the molecular mechanism of integrin inside-out signaling, we generated K562 stable cell lines that expressed LFA-1 (alpha(L)beta(2)) or Mac-1 (alpha(M)beta(2)) with mutations in the cytoplasmic domain. Complete truncation of the beta(2) cytoplasmic domain, but not a truncation that retained the membrane proximal eight residues, resulted in constitutive activation of alpha(L)beta(2) and alpha(M)beta(2), demonstrating the importance of this membrane proximal region in the regulation of integrin adhesive function. Furthermore, replacement of the alpha(L) and beta(2) cytoplasmic domains with acidic and basic peptides that form an alpha-helical coiled coil caused inactivation of alpha(L)beta(2). Association of these artificial cytoplasmic domains was directly demonstrated. By contrast, replacement of the alpha(L) and beta(2) cytoplasmic domains with two basic peptides that do not form an alpha-helical coiled coil activated alpha(L)beta(2). Induction of ligand binding by the activating cytoplasmic domain mutations correlated with the induction of activation epitopes in the extracellular domain. Our data demonstrate that cytoplasmic, membrane proximal association between integrin alpha and beta subunits, constrains an integrin in the inactive conformation.

Source: Journal of Biological Chemistry

DOI: 10.1074/jbc.m100600200

Authors: Chafen Lu, Junichi Takagi, Timothy A. Springer

Institution: Harvard University

Language: English

Topic: Cell Adhesion Molecules Research

Subfield: Immunology and Allergy

Field: Medicine

Domain: Health Sciences

Open Access status: hybrid

Estimated APC paid: $3,430

Funder: National Cancer Institute