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Gene Review

Canx  -  calnexin

Mus musculus

Synonyms: 1110069N15Rik, AI988026, CNX, Calnexin, Cnx, ...
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Disease relevance of Canx

  • The lack of specificity for calnexin interaction reveals a novel role for calreticulin in OCAI albinism [1].
  • We report here the molecular cloning and sequencing of SmIrV1 which contains a deduced amino acid sequence of 582 residues with similarity to three proteins: calnexin, calreticulin, and OvRal1, a surface antigen of the filarial nematode Onchocerca volvulus [2].
  • Analyses with RT-PCR showed that TAP-1, TAP2, LMP-2, LMP7, LMP10, tapasin and calnexin mRNA specific for these genes was absent in metastases produced in immunocompetent mice [3].
  • The molecular chaperone calnexin coimmunoprecipitates with secretion-incompetent variant null(Hong Kong) retained in stably transfected mouse hepatoma cells (Le, A., Steiner, J. L., Ferrell, G. A., Shaker, J. F., and Sifers, R. N. (1994) J. Biol. Chem. 269, 7514-7519) [4].
  • We now report that a small fraction of calnexin is normally expressed on the surface of various cells such as mastocytoma cells, murine splenocytes, fibroblast cells, and human HeLa cells [5].

High impact information on Canx

  • In human B-cell lines, however, class I/beta 2m dimers in the ER are physically associated with TAP molecules rather than calnexin [6].
  • The molecular chaperone function of calnexin (IP90, p88), a 90-kilodalton protein that resides in the endoplasmic reticulum (ER), in the retention of representative chains of the TCR-CD3 complex in the ER was tested [7].
  • Truncation mutants of calnexin, when transiently expressed in COS cells, were exported from the ER and either accumulated in the Golgi or progressed to the cell surface [7].
  • The peptide-loading function was specific to calreticulin, since the defect in K42 could be rectified by transfection with calreticulin but not a soluble form of calnexin, which shares its lectin-like activity [8].
  • The immunoglobulin alpha (Ig alpha)/Ig beta heterodimer was detected on the surface of mu-negative proB cell lines in association with calnexin [9].

Biological context of Canx


Anatomical context of Canx


Associations of Canx with chemical compounds

  • Although not fully interchangeable during assistance of glycoprotein folding, calreticulin and calnexin may work, independently, as efficient and crucial factors for retention in the ER of nonnative polypeptides [15].
  • Notably, this glycan-independent interaction with calnexin significantly retards the degradation of misfolded PLP [19].
  • Calnexin (Cnx), a type-1 integral transmembrane ER protein which is partially homologous to Crt but lacks the KDEL sequence, is not detected on the cell surface either [20].
  • Functional relationship between calreticulin, calnexin, and the endoplasmic reticulum luminal domain of calnexin [11].
  • Involvement of the chaperone protein calnexin and the acetylcholine receptor beta-subunit in the assembly and cell surface expression of the receptor [21].

Physical interactions of Canx

  • Conversely, membrane-anchored calreticulin bound to a similar set of glycoproteins as calnexin [11].
  • However, H2b, which will exit to the Golgi, dissociated from calnexin and remained bound for a longer period to ERp57, whereas the opposite was true for the endoplasmic reticulum-associated degradation substrate H2a that will go to the endoplasmic reticulum-derived quality control compartment [22].
  • During the normal folding pathway, TRP-1 interacts with calnexin [23].
  • SR-A interacts with calnexin and when the association is prevented changes in the recycling kinetics and rate of turnover of the receptor result, leading to enhanced cell surface expression [24].
  • Lectin-deficient calnexin is capable of binding class I histocompatibility molecules in vivo and preventing their degradation [25].

Enzymatic interactions of Canx


Regulatory relationships of Canx

  • Calnexin is thought to retain free class I heavy chains and/or promote their folding and assembly with beta 2-microglobulin and peptide ligand [28].
  • Upon persistent misfolding, tsO45 G was slowly released from calnexin and entered a second level of retention-based ER quality control by forming BiP/GRP78-associated disulfide-bonded aggregates [29].
  • CD3 molecules are expressed on the surface of these cells in association with calnexin [30].

Other interactions of Canx


Analytical, diagnostic and therapeutic context of Canx


  1. Soluble tyrosinase is an endoplasmic reticulum (ER)-associated degradation substrate retained in the ER by calreticulin and BiP/GRP78 and not calnexin. Popescu, C.I., Paduraru, C., Dwek, R.A., Petrescu, S.M. J. Biol. Chem. (2005) [Pubmed]
  2. Molecular cloning and expression of SmIrV1, a Schistosoma mansoni antigen with similarity to calnexin, calreticulin, and OvRal1. Hawn, T.R., Tom, T.D., Strand, M. J. Biol. Chem. (1993) [Pubmed]
  3. MHC class I-deficient metastatic tumor variants immunoselected by T lymphocytes originate from the coordinated downregulation of APM components. Garcia-Lora, A., Martinez, M., Algarra, I., Gaforio, J.J., Garrido, F. Int. J. Cancer (2003) [Pubmed]
  4. Intracellular association between UDP-glucose:glycoprotein glucosyltransferase and an incompletely folded variant of alpha1-antitrypsin. Choudhury, P., Liu, Y., Bick, R.J., Sifers, R.N. J. Biol. Chem. (1997) [Pubmed]
  5. Cell surface expression of calnexin, a molecular chaperone in the endoplasmic reticulum. Okazaki, Y., Ohno, H., Takase, K., Ochiai, T., Saito, T. J. Biol. Chem. (2000) [Pubmed]
  6. MHC class I/beta 2-microglobulin complexes associate with TAP transporters before peptide binding. Ortmann, B., Androlewicz, M.J., Cresswell, P. Nature (1994) [Pubmed]
  7. Retention of unassembled components of integral membrane proteins by calnexin. Rajagopalan, S., Xu, Y., Brenner, M.B. Science (1994) [Pubmed]
  8. Assembly and antigen-presenting function of MHC class I molecules in cells lacking the ER chaperone calreticulin. Gao, B., Adhikari, R., Howarth, M., Nakamura, K., Gold, M.C., Hill, A.B., Knee, R., Michalak, M., Elliott, T. Immunity (2002) [Pubmed]
  9. The Ig alpha/Igbeta heterodimer on mu-negative proB cells is competent for transducing signals to induce early B cell differentiation. Nagata, K., Nakamura, T., Kitamura, F., Kuramochi, S., Taki, S., Campbell, K.S., Karasuyama, H. Immunity (1997) [Pubmed]
  10. Early postnatal death and motor disorders in mice congenitally deficient in calnexin expression. Denzel, A., Molinari, M., Trigueros, C., Martin, J.E., Velmurgan, S., Brown, S., Stamp, G., Owen, M.J. Mol. Cell. Biol. (2002) [Pubmed]
  11. Functional relationship between calreticulin, calnexin, and the endoplasmic reticulum luminal domain of calnexin. Danilczyk, U.G., Cohen-Doyle, M.F., Williams, D.B. J. Biol. Chem. (2000) [Pubmed]
  12. Molecular cloning and sequencing of calnexin-t. An abundant male germ cell-specific calcium-binding protein of the endoplasmic reticulum. Ohsako, S., Hayashi, Y., Bunick, D. J. Biol. Chem. (1994) [Pubmed]
  13. Role of calnexin, calreticulin, and endoplasmic reticulum mannosidase I in apolipoprotein(a) intracellular targeting. Wang, J., White, A.L. Biochemistry (2000) [Pubmed]
  14. Human, mouse, and rat calnexin cDNA cloning: identification of potential calcium binding motifs and gene localization to human chromosome 5. Tjoelker, L.W., Seyfried, C.E., Eddy, R.L., Byers, M.G., Shows, T.B., Calderon, J., Schreiber, R.B., Gray, P.W. Biochemistry (1994) [Pubmed]
  15. Contrasting functions of calreticulin and calnexin in glycoprotein folding and ER quality control. Molinari, M., Eriksson, K.K., Calanca, V., Galli, C., Cresswell, P., Michalak, M., Helenius, A. Mol. Cell (2004) [Pubmed]
  16. Association of calnexin with mutant peripheral myelin protein-22 ex vivo: a basis for "gain-of-function" ER diseases. Dickson, K.M., Bergeron, J.J., Shames, I., Colby, J., Nguyen, D.T., Chevet, E., Thomas, D.Y., Snipes, G.J. Proc. Natl. Acad. Sci. U.S.A. (2002) [Pubmed]
  17. The use of calnexin and calreticulin by cellular and viral glycoproteins. Pieren, M., Galli, C., Denzel, A., Molinari, M. J. Biol. Chem. (2005) [Pubmed]
  18. Changes in endoplasmic reticulum luminal environment affect cell sensitivity to apoptosis. Nakamura, K., Bossy-Wetzel, E., Burns, K., Fadel, M.P., Lozyk, M., Goping, I.S., Opas, M., Bleackley, R.C., Green, D.R., Michalak, M. J. Cell Biol. (2000) [Pubmed]
  19. Role of calnexin in the glycan-independent quality control of proteolipid protein. Swanton, E., High, S., Woodman, P. EMBO J. (2003) [Pubmed]
  20. KDEL proteins are found on the surface of NG108-15 cells. Xiao, G., Chung, T.F., Pyun, H.Y., Fine, R.E., Johnson, R.J. Brain Res. Mol. Brain Res. (1999) [Pubmed]
  21. Involvement of the chaperone protein calnexin and the acetylcholine receptor beta-subunit in the assembly and cell surface expression of the receptor. Keller, S.H., Lindstrom, J., Taylor, P. J. Biol. Chem. (1996) [Pubmed]
  22. Separate roles and different routing of calnexin and ERp57 in endoplasmic reticulum quality control revealed by interactions with asialoglycoprotein receptor chains. Frenkel, Z., Shenkman, M., Kondratyev, M., Lederkremer, G.Z. Mol. Biol. Cell (2004) [Pubmed]
  23. Folding and maturation of tyrosinase-related protein-1 are regulated by the post-translational formation of disulfide bonds and by N-glycan processing. Negroiu, G., Dwek, R.A., Petrescu, S.M. J. Biol. Chem. (2000) [Pubmed]
  24. Inhibition of alpha-glucosidases I and II increases the cell surface expression of functional class A macrophage scavenger receptor (SR-A) by extending its half-life. Tian, G., Wilcockson, D., Perry, V.H., Rudd, P.M., Dwek, R.A., Platt, F.M., Platt, N. J. Biol. Chem. (2004) [Pubmed]
  25. Lectin-deficient calnexin is capable of binding class I histocompatibility molecules in vivo and preventing their degradation. Leach, M.R., Williams, D.B. J. Biol. Chem. (2004) [Pubmed]
  26. Cleavage of calnexin caused by apoptotic stimuli: implication for the regulation of apoptosis. Takizawa, T., Tatematsu, C., Watanabe, K., Kato, K., Nakanishi, Y. J. Biochem. (2004) [Pubmed]
  27. Class I histocompatibility molecule association with phosphorylated calnexin. Implications for rates of intracellular transport. Capps, G.G., Zúñiga, M.C. J. Biol. Chem. (1994) [Pubmed]
  28. Aglycosylated and phosphatidylinositol-anchored MHC class I molecules are associated with calnexin. Evidence implicating the class I-connecting peptide segment in calnexin association. Carreno, B.M., Schreiber, K.L., McKean, D.J., Stroynowski, I., Hansen, T.H. J. Immunol. (1995) [Pubmed]
  29. Persistent glycoprotein misfolding activates the glucosidase II/UGT1-driven calnexin cycle to delay aggregation and loss of folding competence. Molinari, M., Galli, C., Vanoni, O., Arnold, S.M., Kaufman, R.J. Mol. Cell (2005) [Pubmed]
  30. Surface expression and functional competence of CD3-independent TCR zeta-chains in immature thymocytes. Grassi, F., Barbier, E., Porcellini, S., von Boehmer, H., Cazenave, P.A. J. Immunol. (1999) [Pubmed]
  31. Both raft- and non-raft proteins associate with CHAPS-insoluble complexes: some APP in large complexes. Rouvinski, A., Gahali-Sass, I., Stav, I., Metzer, E., Atlan, H., Taraboulos, A. Biochem. Biophys. Res. Commun. (2003) [Pubmed]
  32. Characterization of domains in mice of calnexin-t, a putative molecular chaperone required in sperm fertility, with use of glutathione S-transferase-fusion proteins. Ohsako, S., Janulis, L., Hayashi, Y., Bunick, D. Biol. Reprod. (1998) [Pubmed]
  33. Class II histocompatibility molecules associate with calnexin during assembly in the endoplasmic reticulum. Schreiber, K.L., Bell, M.P., Huntoon, C.J., Rajagopalan, S., Brenner, M.B., McKean, D.J. Int. Immunol. (1994) [Pubmed]
  34. The calnexin homologue cnx1+ in Schizosaccharomyces pombe, is an essential gene which can be complemented by its soluble ER domain. Parlati, F., Dignard, D., Bergeron, J.J., Thomas, D.Y. EMBO J. (1995) [Pubmed]
  35. Immunolocalization of a novel cholesteryl ester hydrolase in the endoplasmic reticulum of murine and human hepatocytes. Fresnedo, O., De Heredia, M.L., Martínez, M.J., Cristóbal, S., Rejas, M.T., Cuezva, J.M., Ochoa, B. Hepatology (2001) [Pubmed]
  36. Trafficking of mutant carboxypeptidase E to secretory granules in a beta-cell line derived from Cpe(fat)/Cpe(fat) mice. Cawley, N.X., Rodriguez, Y.M., Maldonado, A., Loh, Y.P. Endocrinology (2003) [Pubmed]
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