Specific N-Glycans Direct Apical Delivery of Transmembrane, but Not Soluble or Glycosylphosphatidylinositol-anchored Forms of Endolyn in Madin-Darby Canine Kidney Cells

Beth A. Potter, Gudrun Ihrke, Jennifer R. Bruns, Kelly M. Weixel, Ora A. Weisz

Research output: Contribution to journalArticle

47 Citations (Scopus)

Abstract

The sialomucin endolyn is a transmembrane protein with a unique trafficking pattern in polarized Madin-Darby canine kidney cells. Despite the presence of a cytoplasmic tyrosine motif that, in isolation, is sufficient to mediate basolateral sorting of a reporter protein, endolyn predominantly traverses the apical surface en route to lysosomes. Apical delivery of endolyn is disrupted in tunicamycin-treated cells, implicating a role for N-glycosylation in apical sorting. Site-directed mutagenesis of endolyn's eight N-glycosylation sites was used to identify two N-glycans that seem to be the major determinants for efficient apical sorting of the protein. In addition, apical delivery of endolyn was disrupted when terminal processing of N-glycans was blocked using glycosidase inhibitors. Missorting of endolyn occurred independently of the presence or absence of the basolateral sorting signal, because apical delivery was also inhibited by tunicamycin when the cytoplasmic tyrosine motif was mutated. However, we found that apical secretion of a soluble mutant of endolyn was N-glycan independent, as was delivery of glycosylphosphatidylinositol-anchored endolyn. Thus, specific N-glycans are only essential for the apical sorting of transmembrane endolyn, suggesting fundamental differences in the mechanisms by which soluble, glycosylphosphatidylinositol-anchored, and transmembrane proteins are sorted.

Original languageEnglish (US)
Pages (from-to)1407-1416
Number of pages10
JournalMolecular biology of the cell
Volume15
Issue number3
DOIs
StatePublished - Mar 1 2004

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CD164 Antigens
Glycosylphosphatidylinositols
Madin Darby Canine Kidney Cells
Polysaccharides
Tunicamycin
Glycosylation
Tyrosine
Sialomucins
Proteins
Glycoside Hydrolases
Protein Transport
Site-Directed Mutagenesis
Lysosomes

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Cell Biology

Cite this

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title = "Specific N-Glycans Direct Apical Delivery of Transmembrane, but Not Soluble or Glycosylphosphatidylinositol-anchored Forms of Endolyn in Madin-Darby Canine Kidney Cells",
abstract = "The sialomucin endolyn is a transmembrane protein with a unique trafficking pattern in polarized Madin-Darby canine kidney cells. Despite the presence of a cytoplasmic tyrosine motif that, in isolation, is sufficient to mediate basolateral sorting of a reporter protein, endolyn predominantly traverses the apical surface en route to lysosomes. Apical delivery of endolyn is disrupted in tunicamycin-treated cells, implicating a role for N-glycosylation in apical sorting. Site-directed mutagenesis of endolyn's eight N-glycosylation sites was used to identify two N-glycans that seem to be the major determinants for efficient apical sorting of the protein. In addition, apical delivery of endolyn was disrupted when terminal processing of N-glycans was blocked using glycosidase inhibitors. Missorting of endolyn occurred independently of the presence or absence of the basolateral sorting signal, because apical delivery was also inhibited by tunicamycin when the cytoplasmic tyrosine motif was mutated. However, we found that apical secretion of a soluble mutant of endolyn was N-glycan independent, as was delivery of glycosylphosphatidylinositol-anchored endolyn. Thus, specific N-glycans are only essential for the apical sorting of transmembrane endolyn, suggesting fundamental differences in the mechanisms by which soluble, glycosylphosphatidylinositol-anchored, and transmembrane proteins are sorted.",
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Specific N-Glycans Direct Apical Delivery of Transmembrane, but Not Soluble or Glycosylphosphatidylinositol-anchored Forms of Endolyn in Madin-Darby Canine Kidney Cells. / Potter, Beth A.; Ihrke, Gudrun; Bruns, Jennifer R.; Weixel, Kelly M.; Weisz, Ora A.

In: Molecular biology of the cell, Vol. 15, No. 3, 01.03.2004, p. 1407-1416.

Research output: Contribution to journalArticle

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T1 - Specific N-Glycans Direct Apical Delivery of Transmembrane, but Not Soluble or Glycosylphosphatidylinositol-anchored Forms of Endolyn in Madin-Darby Canine Kidney Cells

AU - Potter, Beth A.

AU - Ihrke, Gudrun

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AU - Weixel, Kelly M.

AU - Weisz, Ora A.

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N2 - The sialomucin endolyn is a transmembrane protein with a unique trafficking pattern in polarized Madin-Darby canine kidney cells. Despite the presence of a cytoplasmic tyrosine motif that, in isolation, is sufficient to mediate basolateral sorting of a reporter protein, endolyn predominantly traverses the apical surface en route to lysosomes. Apical delivery of endolyn is disrupted in tunicamycin-treated cells, implicating a role for N-glycosylation in apical sorting. Site-directed mutagenesis of endolyn's eight N-glycosylation sites was used to identify two N-glycans that seem to be the major determinants for efficient apical sorting of the protein. In addition, apical delivery of endolyn was disrupted when terminal processing of N-glycans was blocked using glycosidase inhibitors. Missorting of endolyn occurred independently of the presence or absence of the basolateral sorting signal, because apical delivery was also inhibited by tunicamycin when the cytoplasmic tyrosine motif was mutated. However, we found that apical secretion of a soluble mutant of endolyn was N-glycan independent, as was delivery of glycosylphosphatidylinositol-anchored endolyn. Thus, specific N-glycans are only essential for the apical sorting of transmembrane endolyn, suggesting fundamental differences in the mechanisms by which soluble, glycosylphosphatidylinositol-anchored, and transmembrane proteins are sorted.

AB - The sialomucin endolyn is a transmembrane protein with a unique trafficking pattern in polarized Madin-Darby canine kidney cells. Despite the presence of a cytoplasmic tyrosine motif that, in isolation, is sufficient to mediate basolateral sorting of a reporter protein, endolyn predominantly traverses the apical surface en route to lysosomes. Apical delivery of endolyn is disrupted in tunicamycin-treated cells, implicating a role for N-glycosylation in apical sorting. Site-directed mutagenesis of endolyn's eight N-glycosylation sites was used to identify two N-glycans that seem to be the major determinants for efficient apical sorting of the protein. In addition, apical delivery of endolyn was disrupted when terminal processing of N-glycans was blocked using glycosidase inhibitors. Missorting of endolyn occurred independently of the presence or absence of the basolateral sorting signal, because apical delivery was also inhibited by tunicamycin when the cytoplasmic tyrosine motif was mutated. However, we found that apical secretion of a soluble mutant of endolyn was N-glycan independent, as was delivery of glycosylphosphatidylinositol-anchored endolyn. Thus, specific N-glycans are only essential for the apical sorting of transmembrane endolyn, suggesting fundamental differences in the mechanisms by which soluble, glycosylphosphatidylinositol-anchored, and transmembrane proteins are sorted.

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