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Updated: Aug 10, 2026
10:17
Pulse-chase Analysis of N-linked Sugar Chains from Glycoproteins in Mammalian Cells
Published on: April 28, 2010
N-glycans as apical sorting signals in epithelial cells
P Scheiffele1, J Peränen, K Simons
1Cell Biology Programme, European Molecular Biology Laboratory, Heidelberg, Germany.
Nature
|November 2, 1995
Summary
Carbohydrates act as an apical targeting signal for secretory proteins in Madin-Darby canine kidney cells. Glycosylation directs proteins to the apical surface, influencing protein sorting in biosynthetic traffic.
Area of Science:
- Cell biology
- Molecular biology
- Biochemistry
Background:
- Newly synthesized molecules in Madin-Darby canine kidney (MDCK) cells are sorted in the trans-Golgi network for delivery to apical and basolateral surfaces.
- Sorting relies on signals in cytoplasmic domains for basolateral transmembrane proteins and glycolipid tails for glycosylphosphatidylinositol-linked proteins.
- Apical transmembrane protein signals are hypothesized to be in ectodomains, as truncated forms are secreted apically.
Purpose of the Study:
- To investigate the role of carbohydrates in protein sorting to the apical surface.
- To determine if glycosylation acts as an apical targeting signal for secretory proteins.
Main Methods:
- Utilized Madin-Darby canine kidney (MDCK) cell culture model.
- Investigated the secretion patterns of glycosylated and non-glycosylated growth hormone.
Main Results:
- Non-glycosylated growth hormone was secreted from both apical and basolateral surfaces.
- Glycosylated growth hormone was specifically secreted from the apical surface.
- Demonstrated that carbohydrates function as an apical targeting signal.
Conclusions:
- Glycans play a crucial role in protein sorting during biosynthetic traffic.
- Beyond protein folding, glycosylation actively directs proteins to specific cellular destinations.
- This finding expands the understanding of molecular sorting mechanisms in epithelial cells.
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