User:Susan Corradino
From Proteopedia
|
- Graduate student
- State University of New York, Old Westbury
- Old Westbury, NY, USA
- Education (Biology). B.S. Marine Vertebrate Biology.
Introduction
Calnexin is an integral protein found in the plasma membrane of the endoplasmic reticulum. This protein functions as a chaperone protein , forming a super-complex which aids in the formation of the MHC complex. Without calnexin, the MHC complex would be compromised and ultimately be unable to present the peptide required for the immune response. An interesting additional function of the protein is to ensure that misfolded glycoproteins remain in the ER until they are disposed of by the appropriate regulating structures. Calnexin has also been described as a player in aiding in the proper folding of polypeptides
3D Structure
This molecule is asymmetrical in shape with two unique domains. The long protruding arm of the protein is thought to function with the communication between calnexin and other proteins, specifically ERp57, a secondary chaperon protein in the formation of the MHC I complex, this section of the protein gives the protein a unique crystal structure that is unlike other proteins (Schrag et al 2001). This arm also provides the contact point for all intermolecular communication (Schrag et al 2001). There are two significant disulfide bonds found in the long arm of calnexin, - and Cys361-Cys367 (Schrag et al 2001). Important amino acids in this section of the crystal structure of calnexin include Lys135 and residues of 173-178 found in the lectin domain as well as Trp343 and residues 346-349. This aspect of the crystal structure will allow the arm of the molecule to wrap around associate proteins to form the super complex for the MHC I (Schrag et al 2001).The second domain which is globular lectin in nature provides the ability to monovalently bind glycan.
