title: Cx43 has distinct mobility within plasma-membrane domains, indicative of progressive formation of gap-junction plaques.
abstract: Connexin 43 (Cx43) is a dynamic molecule, having a short half-life of only a few hours. In this study, we use fluorescent-protein-tagged Cx43 variants to examine Cx43 delivery to the cell surface, its residency status in various cell-surface membrane domains and its mobility characteristics. Rapid time-lapse imaging led to the identification of Cx43 being delivered to cell-surface domains that lacked a contacting cell, and also to its localization within membrane protrusions. Fluorescence recovery after photobleaching (FRAP) was used to investigate the mobility state of cell-surface-localized Cx43. Cx43 mobility within clustered cell-surface profiles of Cx43 could be categorized into those with generally a high degree of lateral mobility and those with generally a low degree of lateral mobility. Cx43 mobility was independent of cluster size, yet the C-terminal domain of Cx43 regulated the proportion of gap-junction-like clusters that acquired a low Cx43 mobility state. Collectively, these studies show that Cx43 establishes residency at all cell-surface membrane domains, and progressively acquires assembly states that probably reflect differences in either channel packing and/or its interactions with Cx43-binding proteins.
authors.affiliation: Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario N6A 5C1, Canada.
authors.forename: Jamie
authors.initials: J
authors.lastname: Simek
authors.forename: Jared
authors.initials: J
authors.lastname: Churko
authors.forename: Qing
authors.initials: Q
authors.lastname: Shao
authors.forename: Dale W
authors.initials: DW
authors.lastname: Laird
mesh_terms: D000818:Animals; D001692:Biological Transport; D002450:Cell Communication; D022081:Cell Surface Extensions / Q000378:metabolism / Q000648:ultrastructure; D018031:Connexin 43 / Q000737:chemistry / Q000378:metabolism*; D036681:Fluorescence Recovery After Photobleaching; D017629:Gap Junctions / Q000378:metabolism* / Q000648:ultrastructure; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D018613:Microscopy, Confocal; D017434:Protein Structure, Tertiary / Q000502:physiology; D051381:Rats; D011993:Recombinant Fusion Proteins; D013997:Time Factors
chemical_list: D018031:Connexin 43; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins