title: Association rates of membrane-coupled cell adhesion molecules.
abstract: Thus far, understanding how the confined cellular environment affects the lifetime of bonds, as well as the extraction of complexation rates, has been a major challenge in studies of cell adhesion. Based on a theoretical description of the growth curves of adhesion domains, we present a new (to our knowledge) method to measure the association rate k(on) of ligand-receptor pairs incorporated into lipid membranes. As a proof of principle, we apply this method to several systems. We find that the k(on) for the interaction of biotin with neutravidin is larger than that for integrin binding to RGD or sialyl Lewis(x) to E-selectin. Furthermore, we find k(on) to be enhanced by membrane fluctuations that increase the probability for encounters between the binders. The opposite effect on k(on) could be attributed to the presence of repulsive polymers that mimic the glycocalyx, which points to two potential mechanisms for controlling the speed of protein complexation during the cell recognition process.
authors.affiliation: Institut für Theoretische Physik and Cluster of Excellence Engineering of Advanced Materials, Friedrich-Alexander-Universität, Erlangen, Germany; II. Institut für Theoretische Physik, Universität Stuttgart, Stuttgart, Germany.
authors.forename: Timo
authors.initials: T
authors.lastname: Bihr
authors.affiliation: Institute of Complex Systems 7: Biomechanics Forschungszentrum Jülich, Jülich, Germany; Department of Cell and Developmental Biology, Theodor-Boveri-Institute, Universität Würzburg, Würzburg, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Fenz
authors.affiliation: Physics Department, Biophysics E22, Technische Universität München, München, Germany.
authors.forename: Erich
authors.initials: E
authors.lastname: Sackmann
authors.affiliation: Institute of Complex Systems 7: Biomechanics Forschungszentrum Jülich, Jülich, Germany.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Merkel
authors.affiliation: II. Institut für Theoretische Physik, Universität Stuttgart, Stuttgart, Germany.
authors.forename: Udo
authors.initials: U
authors.lastname: Seifert
authors.affiliation: Aix-Marseille Université, CNRS, CINaM UMR 7325, Marseille, France.
authors.forename: Kheya
authors.initials: K
authors.lastname: Sengupta
authors.affiliation: Institut für Theoretische Physik and Cluster of Excellence Engineering of Advanced Materials, Friedrich-Alexander-Universität, Erlangen, Germany; Institute Ruđer Bošković, Division of Physical Chemistry, Zagreb, Croatia. Electronic address: smith@physik.uni-erlangen.de.
authors.forename: Ana-Sunčana
authors.initials: AS
authors.lastname: Smith
mesh_terms: D001360:Avidin / Q000378:metabolism; D001710:Biotin / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D007700:Kinetics; D008565:Membrane Proteins / Q000378:metabolism*; D008853:Microscopy; D011485:Protein Binding
chemical_list: D015815:Cell Adhesion Molecules; D008565:Membrane Proteins; D001360:Avidin; D001710:Biotin