Anti-Calreticulin/CALR Antibody Picoband® Fluoro647 Conjugated

Calreticulin  also known as  calregulin,   CRP55,   CaBP3,   calsequestrin-like protein, and  endoplasmic reticulum resident protein 60  (ERp60) is a  protein  that in humans is encoded by the  CALR  gene. It is mapped to 19p13.13. Calreticulin is a multifunctional protein that acts as a major Ca (2+) -binding (storage) protein in the lumen of the endoplasmic reticulum. It is also found in the nucleus, suggesting that it may have a role in transcription regulation. Calreticulin binds to the synthetic peptide KLGFFKR, which is almost identical to an amino acid sequence in the DNA-binding domain of the superfamily of nuclear receptors. Calreticulin binds to antibodies in certain sera of systemic lupus and Sjogren patients which contain anti-Ro/SSA antibodies, it is highly conserved among species, and it is located in the endoplasmic and sarcoplasmic reticulum where it may bind calcium. The amino terminus of calreticulin interacts with the DNA-binding domain of the glucocorticoid receptor and prevents the receptor from binding to its specific glucocorticoid response element. Calreticulin can inhibit the binding of androgen receptor to its hormone-responsive DNA element and can inhibit androgen receptor and retinoic acid receptor transcriptional activities in vivo, as well as retinoic acid-induced neuronal differentiation. Thus, calreticulin can act as an important modulator of the regulation of gene transcription by nuclear hormone receptors. Systemic lupus erythematosus is associated with increased autoantibody titers against calreticulin but calreticulin is not a Ro/SS-A antigen. Earlier papers referred to calreticulin as an Ro/SS-A antigen but this was later disproven. Increased autoantibody titer against human calreticulin is found in infants with complete congenital heart block of both the IgG and IgM classes.

Angiogenesis, Cancer, Cancer Metabolism, Cardiovascular, Developmental Biology, Growth Factors, Growth Factors/Hormones, Invasion/Microenvironment, Metabolism, Metabolism Processes, Organogenesis, Pathways and Processes, Response To Hypoxia, Secreted, Signal Transduction, Signaling Pathways, Stem Cells, TGF Beta

Calcium-binding chaperone that promotes folding, oligomeric assembly and quality control in the endoplasmic reticulum (ER) via the calreticulin/calnexin cycle. This lectin interacts transiently with almost all of the monoglucosylated glycoproteins that are synthesized in the ER. Interacts with the DNA-binding domain of NR3C1 and mediates its nuclear export. Involved in maternal gene expression regulation. May participate in oocyte maturation via the regulation of calcium homeostasis (By similarity) .

1. McCauliffe DP, Zappi E, Lieu TS, Michalak M, Sontheimer RD, Capra JD (Jul 1990) . A human Ro/SS-A autoantigen is the homologue of calreticulin and is highly homologous with onchocercal RAL-1 antigen and an aplysia memory molecule. The Journal of Clinical Investigation. 86 (1) : 332–5. 2. Chao MP, Jaiswal S, Weissman-Tsukamoto R, Alizadeh AA, Gentles AJ, Volkmer J, Weiskopf K, Willingham SB, Raveh T, Park CY, Majeti R, Weissman IL (Dec 2010) . Calreticulin is the dominant pro-phagocytic signal on multiple human cancers and is counterbalanced by CD47. Science Translational Medicine. 2 (63) : 63ra94. 3. Michalak M, Lynch J, Groenendyk J, Guo L, Robert Parker JM, Opas M (Nov 2002) . Calreticulin in cardiac development and pathology. Biochimica et Biophysica Acta. 1600 (1–2) : 32–7.