Basolateral sorting of human poliovirus receptor α involves an interaction with the μ1B subunit of the clathrin adaptor complex in polarized epithelial cells

S Ohka, H Ohno, K Tohyama, A Nomoto - Biochemical and biophysical …, 2001 - Elsevier
S Ohka, H Ohno, K Tohyama, A Nomoto
Biochemical and biophysical research communications, 2001Elsevier
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, hPVRα and hPVRδ, 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 hPVRα and hPVRδ in
polarized epithelial cells deficient of native hPVRs. Basolateral sorting of hPVRα was …
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, hPVRα and hPVRδ, 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 hPVRα and hPVRδ in polarized epithelial cells deficient of native hPVRs. Basolateral sorting of hPVRα was observed in Madine-Darby canine kidney cells expressing μ1B, but not in LLC-PK1 porcine kidney cells deficient in μ1B. Distribution of hPVRδ, however, occurred both on the apical and basolateral plasma membranes of these two cell lines. Basolateral sorting of hPVRα was also seen in LLC-PK1 cells that expressed an intact exogenous μ1B, but not in the cells that expressed a mutant μ1B lacking binding ability to tyrosine-containing signals. These results indicate that μ1B is involved in the distribution of hPVRα to the basolateral membrane. Comparative distribution analysis of hPVRα 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 μ1B protein. Thus, basolateral sorting of hPVRα appears to involve the interaction with μ1B through a tyrosine motif existing in the cytoplasmic domain.
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