Proteins undergo numerous modifications, including folding, translocation, and degradation. During such modifications, polypeptides are rarely in a native, stable state. Molecular chaperones are a diverse group of proteins that modulate polypeptide stability through ATP-dependent folding. Many chaperone proteins are found in the endoplasmic reticulum (ER). Calreticulin is a luminal ER protein that is 39% homologous to the ER chaperone protein, calnexin. Calreticulin contains a C-terminal KDEL ER retention signal, and can bind Ca2+, Zn2+, ATP, and the proteins, ERp57 and protein disulfide isomerase. The molecular chaperone activities of calreticulin may include folding of both Asn-linked glycoproteins and non-glycosylated proteins. In addition, calreticulin is a component of MHC I/transporter associated with Ag presentation (TAP) complex where it may function in peptide assembly onto nascent class I molecules. Calreticulin may also function in integrin signaling, since it binds a3-integrin subunits and regulates integrin-mediated metalloprotease secretion. Thus, calreticulin may be involved in Ca2+ storage, cell adhesion, and protein folding.
This antibody is routinely tested by western blot analysis. Other applications were tested at BD Biosciences Pharmingen during antibody development only or reported in the literature.