Page "Calreticulin" Paragraph 4

A similar quality-control chaperone, calnexin, performs the same service for soluble proteins as does calreticulin.

Both proteins, Calnexin and calreticulin, have the function of binding to oligosaccharides containing terminal glucose residues, thereby targeting them for degradation.

In normal cellular function, trimming of glucose residues off the core oligosaccharide added during N-linked glycosylation is a part of protein processing.

If " overseer " enzymes note that residues are misfolded, proteins within the RER will re-add glucose residues so that other Calreticulin / Calnexin can bind to these proteins and prevent them from proceeding to the Golgi.

This leads these aberrantly folded proteins down a path whereby they are targeted for degradation.