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calnexin; major histocompatibility complex class I antigen-binding protein p88; p90; IP90 (CANX)

Function: - molecular chaperone - transiently associates with newly synthesized glycoproteins in the endoplasmic reticulum (ER) - may act in assisting protein assembly &/or in retention within the ER of unassembled protein subunits - activity of protein disulfide isomerase may coincide with release of glycoprotein from calnexin - seems to play a major role in the quality control apparatus of the ER by the retention of incorrectly folded proteins - possibly responsible for retention in the ER of mutant forms of LDL receptor, CFTR, & alpha-1 antitrypsin leading to familial hypercholesterolemia type II, cystic fibrosis, & juvenile pulmonary emphysema, respectively Structure: belongs to the calreticulin family Compartment: - endoplasmic reticulum membrane - melanosome

General

Ca+2 binding protein chaperonin; chaperone phosphoprotein

Properties

SIZE: entity length = 592 aa MW = 68 kD COMPARTMENT: endoplasmic reticulum MOTIF: signal sequence {1-20} 4 X approximate repeats {278-345} MOTIF: 1-1 {278-290} 1-2 {295-307} 1-3 {314-326} 1-4 {333-345} 4 X approximate repeats {348-405} MOTIF: 2-1 {348-358} 2-2 {367-377} 2-3 {381-391} 2-4 {395-405} transmembrane domain {482-502} Ser phosphorylation site {S554} Thr phosphorylation site {T562} Ser phosphorylation site {S564} Ser phosphorylation site {S583}

Database Correlations

OMIM 114217 UniProt P27824 Pfam PF00262 Entrez Gene 821 Kegg hsa:821

References

  1. Ou WJ et al Association of folding intermediates of glycoproteins with calnexin during protein maturation. Nature 364:771 1993 PMID: 8102790
  2. Entrez Gene :accession 821