title: Short-Lived Cages Restrict Protein Diffusion in the Plasma Membrane.
abstract: The plasma membrane is a heterogeneous environment characterized by anomalous diffusion and the presence of microdomains that are molecularly distinct from the bulk membrane. Using single particle tracking of the C-type lectin CD93, we have identified for the first time the transient trapping of transmembrane proteins in cage-like microdomains which restrict protein diffusion. These cages are stabilized by actin-dependent confinement regions, but are separate structures with sizes and lifespans uncorrelated to those of the underlying actin corral. These membrane cages require cholesterol for their strength and stability, with cholesterol depletion decreasing both. Despite this, cages are much larger in size and are longer lived than lipid rafts, suggesting instead that cholesterol-dependent effects on membrane fluidity or molecular packing play a role in cage formation. This diffusional compartment in the plasma membrane has characteristics of both a diffusional barrier and a membrane microdomain, with a size and lifespan intermediate between short-lived microdomains such as lipid rafts and long-lasting diffusional barriers created by the actin cytoskeleton.
authors.affiliation: Department of Microbiology and Immunology, The University of Western Ontario, London, Ontario, N6A 5C1 Canada.|Department of Physics and Astronomy, The University of Western Ontario, London, Ontario, N6A 3K7 Canada.
authors.forename: Maria
authors.initials: M
authors.lastname: Goiko
authors.affiliation: Department of Physics and Astronomy, The University of Western Ontario, London, Ontario, N6A 3K7 Canada.
authors.forename: John R
authors.initials: JR
authors.lastname: de Bruyn
authors.affiliation: Department of Microbiology and Immunology, The University of Western Ontario, London, Ontario, N6A 5C1 Canada.|Centre for Human Immunology, The University of Western Ontario, London, Ontario, N6A 5C1 Canada.
authors.forename: Bryan
authors.initials: B
authors.lastname: Heit
mesh_terms: D002462:Cell Membrane / Q000737:chemistry*; D002784:Cholesterol / Q000032:analysis; D003599:Cytoskeleton / Q000378:metabolism; D004058:Diffusion; D064368:Healthy Volunteers; D006801:Humans; D021962:Membrane Microdomains / Q000737:chemistry*; D009000:Monocytes / Q000737:chemistry; D051920:NK Cell Lectin-Like Receptor Subfamily D / Q000032:analysis*; D013997:Time Factors
chemical_list: D051920:NK Cell Lectin-Like Receptor Subfamily D; D002784:Cholesterol