Recent studies have shown that newly synthesized proteins and glycoproteins are submitted to a quality control mechanism in the rough endoplasmic reticulum (ER). In this report we present two models: One model will illustrate a transient retention in rough ER leading to a further degradation of glycoproteins in the cytosol, (soluble alkaline phosphatase expressed in Man-P-Dol deficient CHO cells lines). The second model will illustrate a strict retention of glycoproteins in rough ER without degradation nor recycling through the Golgi (E1, E2 glycoproteins of Hepatitis C virus in stably transfected UHCV-11.4 cells and in infected Hep G2 cells).

In both cases, oligomannoside structures are markers of these phenomena, either as free soluble released oligomannosides in the case of degradation, or as N-linked oligomannosides for strict retention in rough ER.

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