[Structural basis for trafficking and quality control of glycoproteins by intracellular lectins]

Glycosylation, the most common post-translational modification for proteins, serves diverse functions. Adding sugars to proteins makes the proteins more resistant to proteolytic digestion. Glycosylated proteins can act as markers and receptors to promote cell-cell adhesion. Additionally, they have many essential quality control functions in the cell, such as correct protein folding and facilitating transport of misfolded proteins to the cytosol, which can be degraded.
Glycosylation occurs in...

ER is the primary site for the maturation and folding of soluble and transmembrane secretory proteins. The calnexin cycle is a specific chaperone system that folds and assesses the confirmation of N-glycosylated proteins before they can exit the ER lumen. The primary players of this quality check pipeline are the lectins, ER-resident chaperones, and a glucosyl transferase enzyme. In case the calnexin system in the lumen fails to salvage a misfolded protein, it is transported to the cytoplasm...

The ER, Golgi apparatus, endosomes, and lysosomes work in tandem to modify, sort, and package proteins and lipids. An integrated membrane trafficking network facilitates the back and forth shuttling of molecules within different organelles in the same cell or across the cell membrane.
The transport of soluble and membrane proteins is mediated by transport vesicles that collect cargo from one cellular compartment and deliver it to another by fusing with the target organelle membrane. The Rab...

Cell adhesion is  an essential aspect of multicellularity. While stable cell interactions usually occur between cells of the same type, transient cell interactions occur between cells of different tissue types, such as between neutrophils and endothelial cells. Selectins are one class of cell adhesion molecules (CAMs) that bind carbohydrate ligands to form transient cell adhesion. They are rod-like proteins with a long extracellular part of variable length ending with the lectin domain, which...

Protein glycosylation starts in the ER lumen and continues in the Golgi apparatus. Glycosyltransferases catalyze the addition of sugar molecules or glycosylation of proteins. Usually, these enzymes add sugars to the hydroxyl groups of selected serine or threonine residues to form O-linked glycans or the amino groups of asparagine residues to form N-linked glycans. Different positions on the same polypeptide chain can contain differently linked glycans.
Multiple sugar molecules that may or may...

The glycocalyx is a carbohydrate-rich, fuzzy-appearing layer on the outer surface of the cell membrane. It is highly hydrophilic, because of this it attracts large amounts of water to the cell's surface. This aids the cell's interaction with the watery environment and also helps it to obtain substances dissolved in the water. It is also important for cell identification, self/non-self determination, and embryonic development and is used in cell-to-cell attachments to form tissues.
Components of...