Abstract
Transmembrane helices of integrin alpha and beta subunits have been implicated in the regulation of integrin activity. Two mutations, glycine-708 to asparagine-708 (G708N)and methionine-701 to asparagine-701, in the transmembrane helix of the beta3 subunit enabled integrin alphaIIbbeta3 to constitutively bind soluble fibrinogen. Further characterization of the G708N mutant revealed that it induced alphaIIbbeta3 clustering and constitutive phosphorylation of focal adhesion kinase. This mutation also enhanced the tendency of the transmembrane helix to form homotrimers. These results suggest that homomeric associations involving transmembrane domains provide a driving force for integrin activation. They also suggest a structural basis for the coincidence of integrin activation and clustering.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Amino Acid Substitution
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Animals
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Antibodies, Monoclonal / metabolism
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Biopolymers
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CHO Cells
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Cell Adhesion
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Cell Membrane / chemistry*
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Cricetinae
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Cricetulus
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Dimerization
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Fibrinogen / metabolism
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Fluorescein-5-isothiocyanate
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Focal Adhesion Protein-Tyrosine Kinases
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Ligands
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Microscopy, Fluorescence
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Molecular Sequence Data
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Mutation
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Phosphorylation
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Platelet Glycoprotein GPIIb-IIIa Complex / chemistry*
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Platelet Glycoprotein GPIIb-IIIa Complex / genetics
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Platelet Glycoprotein GPIIb-IIIa Complex / metabolism*
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Protein Conformation
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Protein Structure, Secondary*
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Protein Structure, Tertiary
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Protein-Tyrosine Kinases / metabolism
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Receptor Aggregation
Substances
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Antibodies, Monoclonal
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Biopolymers
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Ligands
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Platelet Glycoprotein GPIIb-IIIa Complex
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Fibrinogen
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Protein-Tyrosine Kinases
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Focal Adhesion Protein-Tyrosine Kinases
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Fluorescein-5-isothiocyanate