N-linked carbohydrates act as lumenal maturation and quality control protein tags.

Protein modifications such as ubiquitination and phosphorylation commonly serve as sorting tags that control the trafficking and stability of a protein within the cytosol. In recent years, N-linked glycans have emerged as key protein modifications for eukaryotic secretory proteins. These modifications support the recruitment of molecular chaperones and sorting receptors, which recognize specific glycoforms. Therefore, glycanases and carbohydrate transferases work in concert with lectin chaperones and receptors to aid in the maturation and quality control of glycoproteins.