title: Influence of organelle geometry on the apparent binding kinetics of peripheral membrane proteins.
abstract: Information processing in living cells frequently involves an exchange of peripheral membrane proteins between the cytosol and organelle membranes. The typical time scale τ of these association-dissociation cycles is commonly quantified in vivo via fluorescence recovery after photobleaching (FRAP). Contrary to common assumptions, we show here that τ values determined by FRAP depend on the size and number of target structures. Hence, FRAP times alone are insufficient to draw conclusions about the proteins' binding kinetics. In contrast, extracting primary molecular association and dissociation rates from FRAP approaches provides a size-independent and therefore robust measure for the proteins' binding kinetics. We support our theoretical considerations with experiments on the small GTPase Arf-1 that transiently associates with Golgi membranes: While Arf-1 recovery times in untreated cells and in cells with disrupted microtubules are significantly different, the molecular kinetic rates are shown to be the same in both cases.
authors.affiliation: Experimental Physics I, University of Bayreuth, Universitätsstrasse 30, D-95440 Bayreuth, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Hoffmann
authors.affiliation: Experimental Physics I, University of Bayreuth, Universitätsstrasse 30, D-95440 Bayreuth, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Fickentscher
authors.affiliation: Experimental Physics I, University of Bayreuth, Universitätsstrasse 30, D-95440 Bayreuth, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Weiss
mesh_terms: D020823:ADP-Ribosylation Factor 1 / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D016466:CHO Cells; D003412:Cricetulus; D036681:Fluorescence Recovery After Photobleaching; D006056:Golgi Apparatus / Q000187:drug effects / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D018613:Microscopy, Confocal; D008954:Models, Biological; D015739:Nocodazole / Q000494:pharmacology; D011336:Probability; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology*; D050257:Tubulin Modulators / Q000494:pharmacology
chemical_list: D050257:Tubulin Modulators; D049452:Green Fluorescent Proteins; D020823:ADP-Ribosylation Factor 1; D015739:Nocodazole