Calreticulin Overexpression Lysate

HEK293T cells in 10-cm dishes were transiently transfected with a non-lipid polymer transfection reagent specially designed and manufactured for large volume DNA transfection. Transfected cells were cultured for 48hrs before collection. The cells were lysed in modified RIPA buffer (25mM Tris-HCl pH7.6, 150mM NaCl, 1% NP-40, 1mM EDTA, 1xProteinase inhibitor cocktail mix, 1mM PMSF and 1mM Na3VO4, and then centrifuged to clarify the lysate. Protein concentration was measured by BCA protein assay kit.

Calreticulin, also called CALR, is an endoplasmic reticulum (ER) protein that functions as a calcium (Ca2+) buffering molecular chaperone (1-3). Together with calnexin and ERp57, calreticulin has a critical role in protein folding and quality control of newly synthesized glycoproteins (1-3). Calreticulin has many diverse functions beyond Ca2+ binding, including cell adhesion, lectin binding, apoptosis, nuclear transport, antigen presentation, and immune response (1-3). Specifically, calreticulin is part of the peptide-loading complex that resides on the ER membrane and is responsible for antigen loading onto MHC class I molecules (1-3). Calreticulin protein has a theoretical molecular weight of 46 kDa and is 417 amino acids (aa) in length (1-3). The protein has three main domains: the N-terminal lectin-like domain, the proline-rich P-domain, and the acidic C-domain which is followed by an ER-retention KDEL signal sequence (1-3).

Given its role in multiple biological processes, it makes sense that calreticulin is implicated in both healthy and disease states. Studies have found that calreticulin mutations were present in patients with myeloproliferative neoplasms (MFN) and essential thrombocythaemia (ET) (4). Calreticulin expression is typically upregulated in most cancer lines, however it is downregulated in some tissues including cervical carcinomas, prostate cancer, and human colon adenocarcinoma (3). High expression of calreticulin on cancer cells is related to tumor cell phagocytosis and is often correlated with, and counteracted by, elevated CD47 expression to prevent cancer cell phagocytosis (3). Calreticulin mutations can serve as a major diagnostic biomarker for MFN and ET and additionally the calreticulin gene may be a potential target for cancer therapeutics (3,4).

References

1. Michalak, M., Groenendyk, J., Szabo, E., Gold, L. I., & Opas, M. (2009). Calreticulin, a multi-process calcium-buffering chaperone of the endoplasmic reticulum. The Biochemical Journal. https://doi.org/10.1042/BJ20081847

2. Fucikova, J., Spisek, R., Kroemer, G., & Galluzzi, L. (2021). Calreticulin and cancer. Cell Research. https://doi.org/10.1038/s41422-020-0383-9

3. Sun, J., Mu, H., Dai, K., & Yi, L. (2017). Calreticulin: a potential anti-cancer therapeutic target. Die Pharmazie. https://doi.org/10.1691/ph.2017.7031

4. Prins, D., Gonzalez Arias, C., Klampfl, T., Grinfeld, J., & Green, A. R. (2020). Mutant Calreticulin in the Myeloproliferative Neoplasms. HemaSphere. https://doi.org/10.1097/HS9.0000000000000333

This product is for research use only and is not approved for use in humans or in clinical diagnosis. Lysates are guaranteed for 6 months from date of receipt.

Array NBL1-08655

• Calreticulin Antibodies
• Calreticulin ELISA Kits
• Calreticulin Lysate
• Calreticulin Protein