Gene Information
Gene Symbol
CRT, HEL-S-99n, RO, SSA, cC1qR
Entrez Gene ID
Gene Name
Chromosomal Location
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. [provided by RefSeq, Jul 2008]
RefSeq DNA
RefSeq mRNA

Gene Ontology (GO)

GO ID Ontology Function Evidence Reference
GO:0000122 Biological process Negative regulation of transcription by RNA polymerase II IDA 8107809
GO:0002502 Biological process Peptide antigen assembly with MHC class I protein complex ISS 11825569
GO:0006355 Biological process Regulation of transcription, DNA-templated TAS 8107808
GO:0006457 Biological process Protein folding TAS 15474971
GO:0006611 Biological process Protein export from nucleus IDA 11149926
Protein Information
Protein Name
Calreticulin, CRP55, ERp60, HACBP, Sicca syndrome antigen A (autoantigen Ro; calreticulin), calregulin, endoplasmic reticulum resident protein 60, epididymis secretory sperm binding protein Li 99n, grp60
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).
Refseq Proteins
Pfam Accession Pfam ID
PF00262 Calreticulin

Protein processing in endoplasmic reticulum
Antigen processing and presentation
Chagas disease (American trypanosomiasis)
Human cytomegalovirus infection
Human T-cell leukemia virus 1 infection
Herpes simplex virus 1 infection
Epstein-Barr virus infection
Human immunodeficiency virus 1 infection


ER-Phagosome pathway
Assembly of Viral Components at the Budding Site
Scavenging by Class A Receptors
Scavenging by Class F Receptors
ATF6 (ATF6-alpha) activates chaperone genes
Calnexin/calreticulin cycle
Antigen Presentation: Folding, assembly and peptide loading of class I MHC

ENSP00000432660 P23528 P23528
    View interactions

Associated Diseases

Disease groupDisease NameReferences
Blood Disorders
Cardiovascular Diseases
Myocardial Ischemia
Endocrine System Diseases
Colorectal Cancer
Esophagus Neoplasm

Gene expression microarray profiles of cumulus cells in lean and overweight-obese polycystic ovary syndrome patients.

Kenigsberg Shlomit, Bentov Yaakov, Chalifa-Caspi Vered, Potashnik Gad, Ofir Rivka, Birk Ohad S
The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev, Ben-Gurion University, Beer-Sheva, Israel.
Mol Hum Reprod. 2009 Feb;15(2):89-103. doi: 10.1093/molehr/gan082. Epub 2009 Jan

Proteomic biomarkers for ovarian cancer risk in women with polycystic ovary syndrome: a systematic review and biomarker database integration.

Galazis Nicolas, Olaleye Olalekan, Haoula Zeina, Layfield Robert, Atiomo William
Division of Human Development, School of Clinical Sciences, University of Nottingham, Queen's Medical Centre Campus, Nottingham University Hospitals, Nottingham, United Kingdom.
Fertil Steril. 2012 Dec;98(6):1590-601.e1. doi: 10.1016/j.fertnstert.2012.08.002.

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