CANX

Description

The CANX (calnexin) is a protein-coding gene located on chromosome 5.

Calnexin (CNX) is a 67kDa integral protein of the endoplasmic reticulum (ER) that appears as a 90kDa, 80kDa, or 75kDa band on western blotting depending on the antibody source. It consists of a large (50 kDa) N-terminal calcium-binding lumenal domain, a single transmembrane helix, and a short (90 residues), acidic cytoplasmic tail. In humans, calnexin is encoded by the gene CANX. Calnexin acts as a chaperone, assisting protein folding and quality control, ensuring only properly folded and assembled proteins proceed through the secretory pathway. It specifically retains unfolded or unassembled N-linked glycoproteins in the ER. Calnexin binds only to N-glycoproteins with GlcNAc2Man9Glc1 oligosaccharides, which result from the sequential action of glucosidases I and II. Glucosidase II can remove the last glucose residue. If the glycoprotein is improperly folded, UGGT (UDP-glucose:glycoprotein glucosyltransferase) adds the glucose residue back to the oligosaccharide, allowing the glycoprotein to bind to calnexin again. This improperly folded glycoprotein remains in the ER, leading to the expression of EDEM/Htm1p, which eventually degrades the misfolded glycoprotein by removing a mannose residue. Yos-9 (OS-9 in humans), a mannose lectin, marks and sorts misfolded glycoproteins for degradation by recognizing exposed mannose residues after α-mannosidase removal. Calnexin associates with the protein folding enzyme ERp57 to catalyze glycoprotein specific disulfide bond formation. It also functions as a chaperone for MHC class I α-chain folding within the ER membrane. As newly synthesized MHC class I α-chains enter the ER, calnexin binds and retains them in a partially folded state.

Calnexin (CANX) is a calcium-binding protein that interacts with newly synthesized monoglucosylated glycoproteins in the endoplasmic reticulum (ER). It assists in protein assembly and retains unassembled protein subunits within the ER. This protein plays a key role in ER quality control by retaining improperly folded proteins. Calnexin is associated with partial T-cell antigen receptor complexes that escape the ER of immature thymocytes, potentially functioning as a signaling complex in thymocyte maturation. Additionally, it may play a role in receptor-mediated endocytosis at the synapse.

CANX is also known as CNX, IP90, P90.

Associated Diseases

WES Whole Exome Sequencing