|Ref Sequence ID||NP_776425.1|
|Protein Existence Status||Reviewed: Experimental evidence at protein level|
|Protein Function||unique ER luminal resident protein; affects many cellular functions, both in the ER lumen and outside of the ER environment ; performs two major functions: chaperoning and regulation of Ca2+ homoeostasis; highly versatile lectin-like chaperone, and it participates during the synthesis of a variety of molecules, including ion channels, surface receptors,integrins and transporters; affects intracellular Ca2+ homoeostasis by modulation of ER Ca2+ storage and transport.|
|Biochemical Properties||an acidic protein containing two Ca2+-binding site, has three cysteine residues, and all of them are located in the hydrophobic N-domain of the protein; Two out of three cysteine residues found in the protein form a disulphide bridge; bovine brain calreticulin has a pI of 4.2|
|Significance in milk||Associated with lipid droplets in milk as found in rat; calcium binding protein in milk|
|PTMs||Depending on species, calreticulin may have one or more potential N-linked glycosylation sites; The glycosylation pattern of the protein seems to be heterogeneous and does not appear to be a conserved property of the protein. The glycosylation of calreticulin is more common in plants than in animal cells; bovine liver calreticulin appears to be glycosylated with two potential N-linked glycosylation sites; carbohydrate composition, GlcNac2Man4 -9 with GlcNAc2Man5 being most abundant in bovine brain calreticulum; rat liver protein is glycosylated with complex hybrid type of oligosaccharide with a terminal galactose residue|
| Site(s) of PTM(s) |
|Predicted Disorder Regions||194-308,339-417|
|TM Helix Prediction||No TM helices|
|Significance of PTMs||glycosylation is species specific and ppossibly a tissue-specific event, and may not be involved directly in its function.|
|Bibliography||1. Matsuoka, K., Seta, K., Yamakawa, Y., Okuyama, T., Shinoda, T., and Isobe, T. (1994) Covalent structure of bovine brain calreticulin. Biochem. J. 298 ( Pt 2), 435–442. |
2. Navazio, L., Baldan, B., Mariani, P., Gerwig, G. J., and Vliegenthart, J. F. (1996) Primary structure of the N-linked carbohydrate chains of Calreticulin from spinach leaves. Glycoconj. J. 13, 977–983.
3. Ostwald, T. J. and MacLennan, D. H. (1974) Isolation of a high affinity calcium-binding protein from sarcoplasmic reticulum. J. Biol. Chem. 249, 974–979.
4. Fliegel, L., Burns, K., MacLennan, D. H., Reithmeier, R. A., and Michalak, M. (1989) Molecular cloning of the high affinity calcium-binding protein (calreticulin) of skeletal muscle sarcoplasmic reticulum. J. Biol. Chem. 264, 21522–21528.
5. Smith, M. J. and Koch, G. L. (1989) Multiple zones in the sequence of calreticulin (CRP55, calregulin, HACBP), a major calcium binding ER/SR protein. EMBO J. 8, 3581–3586.
6. Lewis, M. J., Mazzarella, R. A., and Green, M. (1985) Structure and assembly of the endoplasmic reticulum. The synthesis of three major endoplasmic reticulum proteins during lipopolysaccharide-induced differentiation of murine lymphocytes. J. Biol. Chem. 260, 3050–3057.
7. Ghosal, D., Shappell, N. W., and Keenan, T. W. (1994) Endoplasmic reticulum lumenal proteins of rat mammary gland. Potential involvement in lipid droplet assembly during lactation. Biochim. Biophys. Acta 1200, 175–181