title: In polarized MDCK cells basolateral vesicles arise from clathrin-gamma-adaptin-coated domains on endosomal tubules.
abstract: Human transferrin receptors (TR) and receptors for polymeric immunoglobulins (pIgR) expressed in polarized MDCK cells maintain steady-state, asymmetric distributions on the separate basolateral and apical surfaces even though they are trafficking continuously into and across these cells. The intracellular mechanisms required to maintain these asymmetric distributions have not been located. Here we show that TR and pIgR internalize from both surfaces to a common interconnected endosome compartment that includes tubules with buds coated with clathrin lattices. These buds generate vesicles that carry TR to the basolateral border. The lattices contain gamma-adaptin and are dispersed by treatment with brefeldin A (BFA). Since BFA treatment abrogates the vectorial trafficking of TR in polarized MDCK cells, we propose that the clathrin-coated domains of the endosome tubules contain the polarized sorting mechanism responsible for their preferential basolateral distribution.
authors.affiliation: Medical Research Council Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, England.
authors.forename: C E
authors.initials: CE
authors.lastname: Futter
authors.forename: A
authors.initials: A
authors.lastname: Gibson
authors.forename: E H
authors.initials: EH
authors.lastname: Allchin
authors.forename: S
authors.initials: S
authors.lastname: Maxwell
authors.forename: L J
authors.initials: LJ
authors.lastname: Ruddock
authors.forename: G
authors.initials: G
authors.lastname: Odorizzi
authors.forename: D
authors.initials: D
authors.lastname: Domingo
authors.forename: I S
authors.initials: IS
authors.lastname: Trowbridge
authors.forename: C R
authors.initials: CR
authors.lastname: Hopkins
mesh_terms: D033982:Adaptor Protein Complex gamma Subunits; D000818:Animals; D029681:Arabidopsis Proteins; D001692:Biological Transport; D020126:Brefeldin A; D002352:Carrier Proteins / Q000378:metabolism; D002451:Cell Compartmentation; D002454:Cell Differentiation; D002460:Cell Line; D002462:Cell Membrane; D016764:Cell Polarity; D002966:Clathrin / Q000378:metabolism*; D003517:Cyclopentanes / Q000494:pharmacology; D004285:Dogs; D011992:Endosomes / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D015388:Organelles / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D019056:Receptors, Polymeric Immunoglobulin / Q000378:metabolism; D011990:Receptors, Transferrin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases
chemical_list: D033982:Adaptor Protein Complex gamma Subunits; D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D002966:Clathrin; D003517:Cyclopentanes; D008565:Membrane Proteins; D010940:Plant Proteins; D011500:Protein Synthesis Inhibitors; D019056:Receptors, Polymeric Immunoglobulin; D011990:Receptors, Transferrin; D020126:Brefeldin A; C471983:AT2G32950 protein, Arabidopsis; D044767:Ubiquitin-Protein Ligases