Ger J. Strous

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In many cells endosomal vacuoles show clathrin coats of which the function is unknown. Herein, we show that this coat is predominantly present on early endosomes and has a characteristic bilayered appearance in the electron microscope. By immunoelectron microscopy we show that the coat contains clathrin heavy as well as light chain, but lacks the adaptor(More)
beta-catenin mediates Wnt signaling by acting as the essential co-activator for TCF transcription factors. Wnt signaling increases the half-life and therefore the absolute level of beta-catenin in responding cells. The current model states that these changes in beta-catenin stability set the threshold for Wnt signaling. However, we find that pharmacological(More)
In rats infused with asialoglycoprotein for 60 min, receptor-mediated endocytosis of the ligand occurred exclusively in hepatic parenchymal cells. We have used double-label immunoelectron microscopy on ultrathin cryosections of rat liver to identify the site at which the asialoglycoprotein receptor and its ligand dissociate following their common(More)
The intracellular distributions of the cation-independent mannose 6-phosphate receptor (MPR) and a 120-kD lysosomal membrane glycoprotein (lgp120) were studied in rat hepatoma cells. Using quantitative immunogold cytochemistry we found 10% of the cell's MPR located at the cell surface. In contrast, lgp120 was not detectable at the plasma membrane.(More)
All members of the low density lipoprotein (LDL) receptor family contain at least one copy of the NPXY sequence within their cytoplasmic tails. For the LDL receptor, it has been demonstrated that the NPXY motif serves as a signal for rapid endocytosis through coated pits. Thus, it is generally believed that the NPXY sequences function as endocytosis signals(More)
The ubiquitin-dependent protein degradation system has recently been implicated in downregulation of signal transducing receptors. Growth hormone receptor (GHR) cDNA was transfected into Chinese hamster ovary cells, which exhibit a temperature-sensitive defect in ubiquitin conjugation (CHO-ts20), as well as into wild-type cells (CHO-E36). Upon binding of(More)
Considerable advances have been made in recent years in our understanding of the biochemistry of mucin-type glycoproteins. This class of compounds is characterized mainly by a high level of O-linked oligosaccharides. Initially, the glycoproteins were solely known as the major constituents of mucus. Recent studies have shown that mucins from the(More)
Endocytosed proteins destined for degradation in lysosomes are targeted mainly to early endosomes following uptake. Late endosomes are the major site for entry of newly synthesized lysosomal hydrolases via the cation-independent mannose 6-phosphate receptor into the degradative pathway. No consensus exists as to the mechanism of transport from early to late(More)
Using double-label quantitative immunoelectron microscopy on ultrathin cryosections of rat liver, we have compared the endocytotic pathways of the receptors for asialoglycoprotein (ASGP-R), mannose-6-phosphate ligands (MP-R), and polymeric IgA (IgA-R). All three were found within the Golgi complex, along the entire plasma membrane, in coated pits and(More)
The low density lipoprotein receptor-related protein (LRP) is a multifunctional endocytic receptor with the ability to bind and endocytose several structurally and functionally distinct ligands. A 39 kDa receptor-associated protein (RAP) inhibits all ligand interactions with LRP in vitro. In the present study, we demonstrate that RAP is an endoplasmic(More)