calnexin

CANX
Identifiers
Aliases	CANX, CNX, IP90, P90, calnexin
External IDs	OMIM: 114217 MGI: 88261 HomoloGene: 1324 GeneCards: 821
Gene ontology
Molecular function	• calcium ion binding; • apolipoprotein binding; • unfolded protein binding; • glycoprotein binding; • metal ion binding; • protein binding; • poly(A) RNA binding; • ionotropic glutamate receptor binding; • carbohydrate binding;
Cellular component	• cytoplasm; • integral component of membrane; • ER-mitochondrion membrane contact site; • rough endoplasmic reticulum; • ribosome; • endoplasmic reticulum lumen; • endoplasmic reticulum membrane; • membrane; • melanosome; • myelin sheath; • dendritic spine; • smooth endoplasmic reticulum; • protein complex; • axon; • neuronal cell body; • endoplasmic reticulum; • dendrite cytoplasm; • integral component of lumenal side of endoplasmic reticulum membrane; • extracellular exosome;
Biological process	• cellular protein metabolic process; • antigen processing and presentation of exogenous peptide antigen via MHC class II; • post-translational protein modification; • antigen processing and presentation of peptide antigen via MHC class I; • aging; • protein folding in endoplasmic reticulum; • protein N-linked glycosylation via asparagine; • protein secretion; • clathrin-mediated endocytosis; • synaptic vesicle endocytosis; • protein folding; • chaperone-mediated protein folding;
	Sources:Amigo / QuickGO
RNA expression pattern
	; ;
	More reference expression data
Orthologs
	821
	12330
	ENSG00000127022
	ENSMUSG00000020368
	P27824
	P35564
	NM_001024649; NM_001746
	NM_001110499; NM_001110500; NM_007597
	NP_001019820.1; NP_001737.1
	NP_001103969.1; NP_001103970.1; NP_031623.1
	Wikidata
View/Edit Human	View/Edit Mouse

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/06/28 13:30:21」(JST)

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[Wiki en表示]

Calnexin (CNX) is a 67kDa integral protein (that appears variously as a 90kDa, 80kDa or 75kDa band on western blotting depending on the source of the antibody) of the endoplasmic reticulum (ER). It consists of a large (50 kDa) N-terminal calcium-binding lumenal domain, a single transmembrane helix and a short (90 residues), acidic cytoplasmic tail.

Function

Calnexin is a chaperone, characterized by assisting protein folding and quality control, ensuring that only properly folded and assembled proteins proceed further along the secretory pathway. It specifically acts to retain unfolded or unassembled N-linked glycoproteins in the ER. Calnexin binds only those N-glycoproteins that have GlcNAc2Man9Glc1 oligosaccharides. These monoglucosylated oligosaccharides result from the trimming of two glucose residues by the sequential action of two glucosidases, I and II. Glucosidase II can also remove the third and last glucose residue. If the glycoprotein is not properly folded, an enzyme called UGGT (for UDP-glucose:glycoprotein glucosyltransferase) will add the glucose residue back onto the oligosaccharide thus regenerating the glycoprotein's ability to bind to calnexin. The improperly-folded glycoprotein chain thus loiters in the ER, risking the encounter with MNS1 (alpha-mannosidase), which eventually sentences the underperforming glycoprotein to degradation by removing one of the nine mannose residues. If the protein is correctly translated, the chance of it being correctly folded before it encounters MNS1 is high.

Calnexin also functions as a chaperone for the folding of MHC class I α-chain in the membrane of the ER. As newly synthesized MHC class I α-chains enter the endoplasmic reticulum, calnexin binds on to them retaining them in a partly folded state.^[1] After the β2-microglobulin binds to the MHC class I peptide-loading complex (PLC), calreticulin and ERp57 take over the job of chaperoning the MHC class I protein while the tapasin links the complex to the Transporter associated with antigen processing (TAP) complex. This association prepares the MHC class I for binding an antigen for presentation on the cell surface.

Cofactors

ATP and calcium ions are cofactors involved in substrate binding for calnexin.

References

^ Murphy K (2011). Janeway's Immunobiology (8th ed.). Oxford: Taylor & Francis. ISBN 978-0815342434.

External links

Calnexin at the US National Library of Medicine Medical Subject Headings (MeSH)

UpToDate Contents

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1. 抗原提示細胞 antigen presenting cells

English Journal

The protein ERp57 contributes to EGF receptor signaling and internalization in MDA-MB-468 breast cancer cells.

Gaucci E, Altieri F, Turano C, Chichiarelli S.SourceDepartment of Biochemical Sciences "A. Rossi Fanelli", Sapienza University of Rome, Piazzale Aldo Moro 5, Rome, 00185, Italy; Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Piazzale Aldo Moro 5, Rome, 00185, Italy.
Journal of cellular biochemistry.J Cell Biochem.2013 Nov;114(11):2461-70. doi: 10.1002/jcb.24590.
The disulfide isomerase ERp57 is a soluble protein mainly located in the endoplasmic reticulum, where it acts in the quality control of newly synthesized glycoproteins, in association with calreticulin and calnexin. It has been also detected in other cell compartments, such as the cytosol, the plasm
PMID 23696074

Deficiency of α-glucosidase I alters glycoprotein glycosylation and lifespan in Caenorhabditis elegans.

Katoh T, Takase J, Tani Y, Amamoto R, Aoshima N, Tiemeyer M, Yamamoto K, Ashida H.SourceComplex Carbohydrate Research Center, The University of Georgia, Athens, GA 30602-4712, USA.
Glycobiology.Glycobiology.2013 Oct;23(10):1142-51. doi: 10.1093/glycob/cwt051. Epub 2013 Jul 7.
Endoplasmic reticulum (ER) α-glucosidase I is an enzyme that trims the distal α1,2-linked glucose (Glc) residue from the Glc3Man9GlcNAc2 oligosaccharide following its addition to nascent glycoproteins in the initial step of processing. This reaction is critical to the subsequent processing of N-gl
PMID 23836288

Modulation of endoplasmic reticulum chaperone GRP78 by high glucose in hippocampus of streptozotocin-induced diabetic mice and C6 astrocytic cells.

K Wong DP, T Chu JM, L Hung VK, M Lee DK, K Cheng CH, L Yung KK, M Yue KK.SourceSchool of Chinese Medicine, Hong Kong Baptist University, Hong Kong.
Neurochemistry international.Neurochem Int.2013 Sep 19. pii: S0197-0186(13)00237-4. doi: 10.1016/j.neuint.2013.09.010. [Epub ahead of print]
Diabetes mellitus is known to increase the risk of neurodegeneration, and both diseases are reported to be linked to dysfunction of endoplasmic reticulum (ER). Astrocytes are important in the defense mechanism of central nervous system (CNS), with great ability of tolerating accumulation of toxic su
PMID 24056253

Japanese Journal

Carbon and nitrogen depletion-induced nucleophagy and selective autophagic sequestration of a whole nucleus in multinucleate cells of the filamentous fungus <i>Aspergillus oryzae</i>

The Journal of General and Applied Microbiology, 2017
NAID 130005464983

Effect of ionomycin on interaction of calnexin with vesicular stomatitis virus glycoprotein is cell type-specific

Journal of Oral Science 57(4), 305-312, 2015
NAID 130005130207

Beneficial impact of Gpnmb and its significance as a biomarker in nonalcoholic steatohepatitis

Scientific reports 5, 16920, 2015
NAID 120005697274

Related Pictures

Calreticulin Calnexin Cycle Pictures to Pin on Pinterest - PinsDaddy Anti-Calnexin antibody (Alexa Fluor® 647) [AF18] | Abcam Beyond lectins: the calnexin/calreticulin chaperone system of the endoplasmic Palmitoylation is the switch that assigns calnexin to quality control or ER Ca2 Anti-Calnexin antibody KO Tested (ab22595) | Abcam Anti-Calnexin antibody (ab75801) | Abcam Protein glycosylation and its associated disorders