Mistargeting of the lectin ERGIC-53 to the endoplasmic reticulum of HeLa cells impairs the secretion of a lysosomal enzyme

F Vollenweider, F Kappeler, C Itin… - The Journal of cell biology, 1998 - rupress.org
F Vollenweider, F Kappeler, C Itin, HP Hauri
The Journal of cell biology, 1998rupress.org
ERGIC-53, a homo-oligomeric recycling protein associated with the ER–Golgi intermediate
compartment (ERGIC), has properties of a mannose-selective lectin in vitro, suggesting that
it may function as a transport receptor for glycoproteins in the early secretory pathway. To
investigate if ERGIC-53 is involved in glycoprotein secretion, a mutant form of this protein
was generated that is incapable of leaving the ER. If expressed in HeLa cells in a
tetracycline-inducible manner, this mutant accumulated in the ER and retained the …
ERGIC-53, a homo-oligomeric recycling protein associated with the ER–Golgi intermediate compartment (ERGIC), has properties of a mannose-selective lectin in vitro, suggesting that it may function as a transport receptor for glycoproteins in the early secretory pathway. To investigate if ERGIC-53 is involved in glycoprotein secretion, a mutant form of this protein was generated that is incapable of leaving the ER. If expressed in HeLa cells in a tetracycline-inducible manner, this mutant accumulated in the ER and retained the endogenous ERGIC-53 in this compartment, thus preventing its recycling. Mistargeting of ERGIC-53 to the ER did not alter the gross morphology of the early secretory pathway, including the distribution of β′-COP. However, it impaired the secretion of one major glycoprotein, identified as the precursor of the lysosomal enzyme cathepsin C, while overexpression of wild-type ERGIC-53 had no effect on glycoprotein secretion. Transport of two other lysosomal enzymes and three post-Golgi membrane glycoproteins was unaffected by inactivating the recycling of ERGIC-53. The results suggest that the recycling of ERGIC-53 is required for efficient intracellular transport of a small subset of glycoproteins, but it does not appear to be essential for the majority of glycoproteins.
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