Disease relevance of CALR

• The radioimmunoassay utilizes 125I-labeled calregulin and pansorbin cells (Staphylococcus aureus) coated with rabbit anti-calregulin antibody [1].

High impact information on CALR

• The findings suggest that discrete populations of nonnative conformations are selectively reglucosylated to participate in the calnexin/calreticulin chaperone pathway [2].
• Calnexin and calreticulin are lectin-like molecular chaperones that promote folding and assembly of newly synthesized glycoproteins in the endoplasmic reticulum [3].
• Scatchard analysis of equilibrium dialysis studies have revealed that in the presence of 3.0 mM MgCl2 and 150 mM KCl, calregulin has a single binding site for Ca2+ with an apparent dissociation constant (apparent Kd) of 0.05 microM and 14 binding sites for Zn2+ with apparent Kd(Zn2+) of 310 microM [4].
• Thrombospondin signaling through the calreticulin/LDL receptor-related protein co-complex stimulates random and directed cell migration [5].
• Calreticulin is a binding protein for muramyl dipeptide and peptidoglycan in RK13 cells [6].

Biological context of CALR

• Glycosylation of calreticulin, however, appeared to be a species-specific modification, as Asn162 is replaced by Asp in the sequences already determined for a number of species [7].
• The polypeptide sequence determined was compatible with the sequence of calreticulin deduced from cDNA of different sources, with a number of differences presumably due to species-specific amino acid substitutions [7].
• The deduced amino-acid sequence of the novel clone shares high similarity with mouse calreticulin in the C-terminal 318 amino acids [8].
• We report here the isolation and sequencing of cDNA clones from a bovine brain lambda gt11 cDNA library, two of which appear to code for calreticulin and a third for a novel isoform of calreticulin [8].
• Kinetics and the mechanism of interaction of the endoplasmic reticulum chaperone, calreticulin, with monoglucosylated (Glc1Man9GlcNAc2) substrate [9].

Anatomical context of CALR

• The covalent structure of bovine brain calreticulin, a major Ca(2+)-binding protein in the lumen of the endoplasmic reticulum, was determined by analysis of the purified protein [7].
• Calreticulin-null and LRP-null fibroblasts do not migrate in response to TSP1/hep I, nor do endothelial cells treated with the LRP inhibitor receptor-associated protein (RAP) [5].
• Calregulin was quantitated in various bovine tissue extracts and was detected in all tissues except erythrocytes [1].
• Calreticulin (CRT) was isolated and identified as a protein in rabbit kidney RK(13) cells that binds the apoptogenic bacterial cell wall (BCW) components, muramyl dipeptide (MDP) and peptidoglycan (PG) [6].
• CRT is a calcium-binding protein involved in multiple cell functions and possibly implicated in parasites host immune system evasion [10].

Associations of CALR with chemical compounds

• This study shows that accumulation of xanthurenic acid in the lens epithelial cells leads to an overexpression of endoplasmic reticulum (ER) resident stress chaperones proteins, glucose-regulated protein (Grp94), and calreticulin [11].
• After ammonium sulfate precipitation, the proteins were purified by chromatography; BiP was purified by affinity chromatography on ATP-agarose, and both endoplasmin and calreticulin were purified by affinity chromatography on Con A-Sepharose [12].
• The expression of calreticulin was augmented in vascular cells exposed to high glucose in comparison with low-glucose conditions [13].

Physical interactions of CALR

• Using RNA mobility shift, UV cross-linking, and in vitro degradation assays, followed by mass-spectrometric analysis, we identified calreticulin as a specific destabilizing trans-acting factor that binds to a 10-nucleotide cis-acting element (CAE(2181-2190)) in the 3'-untranslated region of GLUT-1 mRNA [13].

Other interactions of CALR

• CL-43 as well as conglutinin, binds to the collectin receptor (C1qR) localized on many types of cells identified as a surface variant of calreticulin [14].
• Inhibition of phospholipase A2 activity by calmodulin, S-100, calregulin, parvalbumin, troponin-C, or CAB-48 was not observed [15].

Analytical, diagnostic and therapeutic context of CALR

• The binding of calreticulin to IgG was used for the development of immunoassay and the relative affinity of the lectin-substrate association was indirectly measured [9].
• Development of a radioimmunoassay for quantitation of calregulin in bovine tissues [1].
• Gel permeation chromatography of bovine brain 100 000 g supernatant in the presence or absence of calcium has resolved a single peak of calregulin by RIA [1].
• Expression analyses of the corresponding gene in different developmental stages and tissues were performed by RT-PCR and Western-blot, which indicated a ubiquitous expression of the B. microplus calreticulin gene and demonstrated its presence in saliva [10].

References