title: Basolateral sorting of human poliovirus receptor alpha involves an interaction with the mu1B subunit of the clathrin adaptor complex in polarized epithelial cells.
abstract: Poliovirus receptor (hPVR/CD155) is a cell surface glycoprotein that belongs to the immunoglobulin superfamily but its natural function remains unknown. Two membrane-bound isoforms, hPVRalpha and hPVRdelta, are known to date, and they differ only in the amino acid sequence of their cytoplasmic domains. To gain an insight into the possible function of the cytoplasmic domains, we examined the localization of introduced hPVRalpha and hPVRdelta in polarized epithelial cells deficient of native hPVRs. Basolateral sorting of hPVRalpha was observed in Madine-Darby canine kidney cells expressing mu1B, but not in LLC-PK1 porcine kidney cells deficient in mu1B. Distribution of hPVRdelta, however, occurred both on the apical and basolateral plasma membranes of these two cell lines. Basolateral sorting of hPVRalpha was also seen in LLC-PK1 cells that expressed an intact exogenous mu1B, but not in the cells that expressed a mutant mu1B lacking binding ability to tyrosine-containing signals. These results indicate that mu1B is involved in the distribution of hPVRalpha to the basolateral membrane. Comparative distribution analysis of hPVRalpha using a series of mutants with truncations and substitutions in the cytoplasmic tail demonstrated that determinant for the basolateral sorting resided in the tyrosine-containing motif of the cytoplasmic tail. Furthermore, yeast two hybrid analysis strongly suggested that the tyrosine motif directly interacted with mu1B protein. Thus, basolateral sorting of hPVRalpha appears to involve the interaction with mu1B through a tyrosine motif existing in the cytoplasmic domain.
authors.affiliation: Department of Microbiology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Ohka
authors.forename: H
authors.initials: H
authors.lastname: Ohno
authors.forename: K
authors.initials: K
authors.lastname: Tohyama
authors.forename: A
authors.initials: A
authors.lastname: Nomoto
mesh_terms: D033961:Adaptor Protein Complex 1; D033983:Adaptor Protein Complex mu Subunits; D033942:Adaptor Proteins, Vesicular Transport; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002460:Cell Line; D016764:Cell Polarity / Q000502:physiology*; D004285:Dogs; D004847:Epithelial Cells / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D020033:Protein Isoforms; D021382:Protein Sorting Signals / Q000502:physiology*; D021122:Protein Subunits; D021381:Protein Transport; D011991:Receptors, Virus / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D020798:Two-Hybrid System Techniques
chemical_list: C499064:AP1M2 protein, human; D033961:Adaptor Protein Complex 1; D033983:Adaptor Protein Complex mu Subunits; D033942:Adaptor Proteins, Vesicular Transport; D002352:Carrier Proteins; D008565:Membrane Proteins; D020033:Protein Isoforms; D021382:Protein Sorting Signals; D021122:Protein Subunits; D011991:Receptors, Virus; D011993:Recombinant Fusion Proteins; C499065:adaptor protein complex 1, mu 2 subunit; C066100:poliovirus receptor