title: The MARVEL transmembrane motif of occludin mediates oligomerization and targeting to the basolateral surface in epithelia.
abstract: Occludin (Ocln), a MARVEL-motif-containing protein, is found in all tight junctions. MARVEL motifs are comprised of four transmembrane helices associated with the localization to or formation of diverse membrane subdomains by interacting with the proximal lipid environment. The functions of the Ocln MARVEL motif are unknown. Bioinformatics sequence- and structure-based analyses demonstrated that the MARVEL domain of Ocln family proteins has distinct evolutionarily conserved sequence features that are consistent with its basolateral membrane localization. Live-cell microscopy, fluorescence resonance energy transfer (FRET) and bimolecular fluorescence complementation (BiFC) were used to analyze the intracellular distribution and self-association of fluorescent-protein-tagged full-length human Ocln or the Ocln MARVEL motif excluding the cytosolic C- and N-termini (amino acids 60-269, FP-MARVEL-Ocln). FP-MARVEL-Ocln efficiently arrived at the plasma membrane (PM) and was sorted to the basolateral PM in filter-grown polarized MDCK cells. A series of conserved aromatic amino acids within the MARVEL domain were found to be associated with Ocln dimerization using BiFC. FP-MARVEL-Ocln inhibited membrane pore growth during Triton-X-100-induced solubilization and was shown to increase the membrane-ordered state using Laurdan, a lipid dye. These data demonstrate that the Ocln MARVEL domain mediates self-association and correct sorting to the basolateral membrane.
authors.affiliation: Department of Pathology, Sackler School of Medicine,  Tel-Aviv 69978, Israel.
authors.forename: Yakey
authors.initials: Y
authors.lastname: Yaffe
authors.forename: Jeanne
authors.initials: J
authors.lastname: Shepshelovitch
authors.forename: Inbar
authors.initials: I
authors.lastname: Nevo-Yassaf
authors.forename: Adva
authors.initials: A
authors.lastname: Yeheskel
authors.forename: Hedva
authors.initials: H
authors.lastname: Shmerling
authors.forename: Joanna M
authors.initials: JM
authors.lastname: Kwiatek
authors.forename: Katharina
authors.initials: K
authors.lastname: Gaus
authors.forename: Metsada
authors.initials: M
authors.lastname: Pasmanik-Chor
authors.forename: Koret
authors.initials: K
authors.lastname: Hirschberg
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D018929:Cell Culture Techniques; D002462:Cell Membrane / Q000378:metabolism; D002522:Chlorocebus aethiops; D019295:Computational Biology; D004285:Dogs; D004848:Epithelium / Q000378:metabolism; D006801:Humans; D061985:Madin Darby Canine Kidney Cells; D008856:Microscopy, Fluorescence; D008958:Models, Molecular; D008969:Molecular Sequence Data; D062793:Occludin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
chemical_list: D062793:Occludin