Abstract
Clustering of the T cell integrin, LFA-1, at specialized regions of intercellular contact initiates integrin-mediated adhesion and downstream signaling, events that are necessary for a successful immunological response. But how clustering is achieved and sustained is not known. Here we establish that an LFA-1-associated molecule, PTA-1, is localized to membrane rafts and binds the carboxyl-terminal domain of isoforms of the actin-binding protein 4.1G. Protein 4.1 is known to associate with the membrane-associated guanylate kinase homologue, human discs large. We show that the carboxyl-terminal peptide of PTA-1 also can bind human discs large and that the presence or absence of this peptide greatly influences binding between PTA-1 and different isoforms of 4.1G. T cell stimulation with phorbol ester or PTA-1 cross-linking induces PTA-1 and 4.1G to associate tightly with the cytoskeleton, and the PTA-1 from such activated cells now can bind to the amino-terminal region of 4.1G. We propose that these dynamic associations provide the structural basis for a regulated molecular adhesive complex that serves to cluster and transport LFA-1 and associated molecules.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adaptor Proteins, Signal Transducing
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Amino Acid Sequence
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Animals
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Antigens, Differentiation, T-Lymphocyte / chemistry*
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Antigens, Differentiation, T-Lymphocyte / genetics
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Antigens, Differentiation, T-Lymphocyte / metabolism*
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Binding Sites
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Biological Transport
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CHO Cells
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Cell Membrane / chemistry
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Cell Membrane / ultrastructure
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Cricetinae
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Cross-Linking Reagents
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Cytoskeletal Proteins / chemistry
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Cytoskeletal Proteins / metabolism*
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Cytoskeleton / metabolism
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Discs Large Homolog 1 Protein
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Glutathione Transferase / genetics
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Humans
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Jurkat Cells
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Membrane Proteins / chemistry
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Membrane Proteins / metabolism*
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Models, Molecular
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Molecular Sequence Data
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Mutagenesis, Site-Directed
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Protein Isoforms / metabolism
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Proteins / chemistry
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Proteins / metabolism*
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Recombinant Fusion Proteins
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Saccharomyces cerevisiae / genetics
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T-Lymphocytes / chemistry*
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Transfection
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Two-Hybrid System Techniques
Substances
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Adaptor Proteins, Signal Transducing
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Antigens, Differentiation, T-Lymphocyte
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CD226 antigen
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Cross-Linking Reagents
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Cytoskeletal Proteins
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DLG1 protein, human
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Discs Large Homolog 1 Protein
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Membrane Proteins
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Protein Isoforms
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Proteins
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Recombinant Fusion Proteins
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erythrocyte membrane band 4.1 protein
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Glutathione Transferase