Targeting of an apical endosomal protein to endosomes in Madin-Darby canine kidney cells requires two sorting motifs

K. E. Gokay, Jean Wilson

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

The efficient sorting and targeting of endocytosed macromolecules is critical for epithelial function. However, the distribution of endosomal compartments in these cells remains controversial. In this study, we show that polarized Madin-Darby canine kidney (MDCK) cells target the apical endosomal protein endotubin into an apical early endosomal compartment that is distinct from the apical recycling endosomes. Furthermore, through a panel of site-directed mutations we show that signals required for apical endosomal targeting of endotubin are composed of two distinct motifs on the cytoplasmic domain, a hydrophobic motif and a consensus casein kinase II site. Endotubin-positive endosomes in MDCK cells do not label with basolaterally internalized transferrin or ricin, do not contain the small guanosine triphosphate-binding protein rab11, and do not tubulate in response to low concentrations of brefeldin-A (BFA). Nevertheless, high concentrations of BFA reversibly inhibits the sorting of endotubin from transferrin and cause colocalization in tubular endosomes. These results indicate that, in polarized cells, endotubin targets into a distinct subset of apical endosomes, and the targeting information required both for polarity and endosomal targeting is provided by the cytoplasmic portion of the molecule.

Original languageEnglish (US)
Pages (from-to)354-365
Number of pages12
JournalTraffic
Volume1
Issue number4
StatePublished - 2000

Fingerprint

Brefeldin A
Madin Darby Canine Kidney Cells
Endosomes
Transferrin
Sorting
Ricin
Casein Kinase II
Guanosine Triphosphate
Macromolecules
Recycling
Labels
Carrier Proteins
Proteins
Molecules
Endocytosis
Mutation

Keywords

  • Apical
  • Endosomes
  • Epithelia
  • Membrane trafficking

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Genetics
  • Molecular Biology
  • Structural Biology

Cite this

Targeting of an apical endosomal protein to endosomes in Madin-Darby canine kidney cells requires two sorting motifs. / Gokay, K. E.; Wilson, Jean.

In: Traffic, Vol. 1, No. 4, 2000, p. 354-365.

Research output: Contribution to journalArticle

@article{3d7ef6b32c1c4e808aadc06da4f9fd80,
title = "Targeting of an apical endosomal protein to endosomes in Madin-Darby canine kidney cells requires two sorting motifs",
abstract = "The efficient sorting and targeting of endocytosed macromolecules is critical for epithelial function. However, the distribution of endosomal compartments in these cells remains controversial. In this study, we show that polarized Madin-Darby canine kidney (MDCK) cells target the apical endosomal protein endotubin into an apical early endosomal compartment that is distinct from the apical recycling endosomes. Furthermore, through a panel of site-directed mutations we show that signals required for apical endosomal targeting of endotubin are composed of two distinct motifs on the cytoplasmic domain, a hydrophobic motif and a consensus casein kinase II site. Endotubin-positive endosomes in MDCK cells do not label with basolaterally internalized transferrin or ricin, do not contain the small guanosine triphosphate-binding protein rab11, and do not tubulate in response to low concentrations of brefeldin-A (BFA). Nevertheless, high concentrations of BFA reversibly inhibits the sorting of endotubin from transferrin and cause colocalization in tubular endosomes. These results indicate that, in polarized cells, endotubin targets into a distinct subset of apical endosomes, and the targeting information required both for polarity and endosomal targeting is provided by the cytoplasmic portion of the molecule.",
keywords = "Apical, Endosomes, Epithelia, Membrane trafficking",
author = "Gokay, {K. E.} and Jean Wilson",
year = "2000",
language = "English (US)",
volume = "1",
pages = "354--365",
journal = "Traffic",
issn = "1398-9219",
publisher = "Blackwell Munksgaard",
number = "4",

}

TY - JOUR

T1 - Targeting of an apical endosomal protein to endosomes in Madin-Darby canine kidney cells requires two sorting motifs

AU - Gokay, K. E.

AU - Wilson, Jean

PY - 2000

Y1 - 2000

N2 - The efficient sorting and targeting of endocytosed macromolecules is critical for epithelial function. However, the distribution of endosomal compartments in these cells remains controversial. In this study, we show that polarized Madin-Darby canine kidney (MDCK) cells target the apical endosomal protein endotubin into an apical early endosomal compartment that is distinct from the apical recycling endosomes. Furthermore, through a panel of site-directed mutations we show that signals required for apical endosomal targeting of endotubin are composed of two distinct motifs on the cytoplasmic domain, a hydrophobic motif and a consensus casein kinase II site. Endotubin-positive endosomes in MDCK cells do not label with basolaterally internalized transferrin or ricin, do not contain the small guanosine triphosphate-binding protein rab11, and do not tubulate in response to low concentrations of brefeldin-A (BFA). Nevertheless, high concentrations of BFA reversibly inhibits the sorting of endotubin from transferrin and cause colocalization in tubular endosomes. These results indicate that, in polarized cells, endotubin targets into a distinct subset of apical endosomes, and the targeting information required both for polarity and endosomal targeting is provided by the cytoplasmic portion of the molecule.

AB - The efficient sorting and targeting of endocytosed macromolecules is critical for epithelial function. However, the distribution of endosomal compartments in these cells remains controversial. In this study, we show that polarized Madin-Darby canine kidney (MDCK) cells target the apical endosomal protein endotubin into an apical early endosomal compartment that is distinct from the apical recycling endosomes. Furthermore, through a panel of site-directed mutations we show that signals required for apical endosomal targeting of endotubin are composed of two distinct motifs on the cytoplasmic domain, a hydrophobic motif and a consensus casein kinase II site. Endotubin-positive endosomes in MDCK cells do not label with basolaterally internalized transferrin or ricin, do not contain the small guanosine triphosphate-binding protein rab11, and do not tubulate in response to low concentrations of brefeldin-A (BFA). Nevertheless, high concentrations of BFA reversibly inhibits the sorting of endotubin from transferrin and cause colocalization in tubular endosomes. These results indicate that, in polarized cells, endotubin targets into a distinct subset of apical endosomes, and the targeting information required both for polarity and endosomal targeting is provided by the cytoplasmic portion of the molecule.

KW - Apical

KW - Endosomes

KW - Epithelia

KW - Membrane trafficking

UR - http://www.scopus.com/inward/record.url?scp=0034172864&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0034172864&partnerID=8YFLogxK

M3 - Article

C2 - 11208120

AN - SCOPUS:0034172864

VL - 1

SP - 354

EP - 365

JO - Traffic

JF - Traffic

SN - 1398-9219

IS - 4

ER -