CALR Human

Calreticulin (CALR) is a multifunctional protein primarily located within the endoplasmic reticulum where it serves as a major calcium-binding protein. It plays a crucial role in calcium homeostasis within this organelle. Beyond its function in the endoplasmic reticulum, CALR is also found in the nucleus, where it participates in the regulation of gene transcription. Notably, CALR interacts with a specific amino acid sequence (KLGFFKR) that closely resembles a region within the DNA-binding domain of nuclear receptors, a superfamily of transcription factors. This interaction suggests a mechanism by which CALR may influence gene expression. CALR has been identified as an autoantigen, meaning it is targeted by antibodies in the sera of certain individuals with autoimmune disorders such as systemic lupus and Sjogren's syndrome, particularly those with anti-Ro/SSA antibodies. The protein exhibits a high degree of conservation across different species, highlighting its fundamental biological importance. CALR's ability to modulate the activity of nuclear hormone receptors is noteworthy. For instance, it can hinder the glucocorticoid receptor from binding to its specific DNA response element, thereby influencing glucocorticoid signaling. Similarly, CALR can interfere with the androgen receptor's interaction with its hormone-responsive DNA element, ultimately suppressing both androgen receptor and retinoic acid receptor transcriptional activities. Moreover, CALR has been shown to inhibit retinoic acid-induced neuronal differentiation. These findings collectively suggest that CALR functions as a crucial regulator of gene transcription, particularly in pathways governed by nuclear hormone receptors.

Recombinant human CALR protein, expressed in E. coli, is a single polypeptide chain that lacks glycosylation. This protein consists of 421 amino acids (residues 18-417) and possesses a molecular weight of 48.7 kDa. A 21 amino acid His-Tag is fused to the N-terminus to facilitate purification, which is achieved using standard chromatography techniques.

A clear, colorless solution that has been sterilized by filtration.

The CALR Human solution is formulated in a buffer containing 20mM Tris-HCl (pH 8.0), 1mM DTT, 0.1M NaCl, and 10% glycerol.

For short-term storage (up to 4 weeks), the product should be stored at 4°C. Long-term storage requires freezing at -20°C. The addition of a carrier protein (0.1% HSA or BSA) is recommended for extended storage durations. Repeated freezing and thawing should be avoided to maintain product integrity.

The purity of the CALR Human Recombinant protein is determined by SDS-PAGE analysis and is greater than 85%.

cC1qR, CRT, FLJ26680, RO, SSA, CRP55, Calreticulin, ERp60, CRTC, CALR.

Escherichia Coli.

MGSSHHHHHH SSGLVPRGSH MEPAVYFKEQ FLDGDGWTSR WIESKHKSDF GKFVLSSGKF YGDEEKDKGL QTSQDARFYA LSASFEPFSN KGQTLVVQFT VKHEQNIDCG GGYVKLFPNS LDQTDMHGDS EYNIMFGPDI CGPGTKKVHV IFNYKGKNVL INKDIRCKDD EFTHLYTLIV RPDNTYEVKI DNSQVESGSL EDDWDFLPPK KIKDPDASKP EDWDERAKID DPTDSKPEDW DKPEHIPDPD AKKPEDWDEE MDGEWEPPVI QNPEYKGEWK PRQIDNPDYK GTWIHPEIDN PEYSPDPSIY AYDNFGVLGL DLWQVKSGTI FDNFLITNDE AYAEEFGNET WGVTKAAEKQ MKDKQDEEQR LKEEEEDKKR KEEEEAEDKE DDEDKDEDEE DEEDKEEDEE EDVPGQAKDE L.