Cellular functions of endoplasmic reticulum chaperones calreticulin, calnexin, and ERp57.
Glycosylated proteins destined for the cell surface or to be secreted from the cell are trafficked through the endoplasmic reticulum during synthesis and folding. Correct folding is determined in large part by the sequence of the protein, but it is also assisted by interaction with enzymes and chaperones of the endoplasmic reticulum. Calreticulin, calnexin, and ERp57 are among the endoplasmic chaperones that interact with partially folded glycoproteins and determine if the proteins are to be released from the endoplasmic reticulum to be expressed, or alternatively, if they are to be sent to the proteosome for degradation. Studies on the effect of alterations in the expression and function of these proteins are providing information about the importance of this quality control system, as well as uncovering other important functions these proteins play outside of the endoplasmic reticulum.
Bedard
Karen
K
Membrane Protein Research Group and Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7.
Szabo
Eva
E
Michalak
Marek
M
Opas
Michal
M
D000818:Animals; D001673:Biodegradation, Environmental; D037281:Calnexin / Q000502:physiology*; D037282:Calreticulin / Q000502:physiology*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006031:Glycosylation; D006360:Heat-Shock Proteins / Q000502:physiology*; D006801:Humans; D018832:Molecular Chaperones / Q000502:physiology*; D019704:Protein Disulfide-Isomerases / Q000502:physiology*; D017510:Protein Folding; D021381:Protein Transport
D037282:Calreticulin; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D037281:Calnexin; D019704:Protein Disulfide-Isomerases; C085868:PDIA3 protein, human