3D Single-Particle Tracking and Optical Trap Measurements on Adhesion Proteins

I.M. Peters, Yvette van Kooyk, Sandra J. van Vliet, B.G. de Grooth, Carl Figdor, Jan Greve

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    Abstract

    A three-dimensional single-particle tracking system was combined with an optical trap to investigate the behavior of transmembrane adhesion proteins. We exploited this setup to investigate which part of the cell adhesion protein LFA-1 forms a connection to the cytoskeleton after binding to its ligand ICAM-1. LFA-1 is an integrin consisting of an α and a ß chain. Thus far, only the cytoplasmic tail of the ß chain is known to form a connection to the cytoskeleton. We investigated cells that express a mutant form of LFA-1 that lacks the complete ß cytoplasmic tail and therefore is not thought to bind to the cytoskeleton. Interestingly, single-particle tracking measurements using beads coated with the ligand ICAM-1 indicate that this mutant form of LFA-1 does not move freely within the cell membrane, suggesting that LFA-1 is still connected to the cytoskeleton network. This finding is strongly supported by the observation that LFA-1 exhibits a more diffusive motion when the cytoskeleton network is disrupted and confirmed by the optical trap measurements used to force the proteins to move through the membrane. Collectively, our findings suggest that the interaction of LFA-1 with the cytoskeleton cannot solely be attributed to the cytoplasmic part of the ß chain.
    Original languageUndefined
    Pages (from-to)189-194
    Number of pages6
    JournalCytometry
    Volume36
    Issue number3
    DOIs
    Publication statusPublished - 1999

    Keywords

    • LFA-1
    • cytoskeleton
    • Optical tweezers
    • METIS-128431
    • 3-D
    • Single-particle tracking
    • IR-60735
    • protein diffusion

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