Caenorhabditis elegans calnexin is N-glycosylated and required for stress response.
Calnexin, a type I integral Ca(2+)-binding protein in the endoplasmic reticulum (ER) membrane, has been implicated in various biological functions including chaperone activity, calcium homeostasis, phagocytosis, and ER stress-induced apoptosis. Caenorhabditis elegans CNX-1 is expressed in the H-shaped excretory cell, intestine, dorsal and ventral nerve cord, spermatheca, and head and tail neurons throughout development. A cnx-1 null mutant displays temperature-sensitive developmental and reproductive defects, and retarded growth under stress. Moreover, a double knockout mutant of calnexin and calreticulin exhibits additive severe defects. Interestingly, both cnx-1 transcript and protein levels are elevated under stress conditions suggesting that CNX-1 may be important for stress-induced chaperoning functions in C. elegans. Glycosidase treatment and site-directed mutagenesis confirmed that CeCNX-1 is N-glycosylated at two asparagine residues of Asn(203) and Asn(571). When transgenic animals from cnx-1 mutant were generated, a glycosylation defective construct failed to rescue phenotypes of cnx-1 mutant suggesting that glycosylation is important for calnexin's functions in C. elegans.
Lee
Wonhae
W
Department of Life Science, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea.
Lee
Tae Hoon
TH
Park
Byung-Jae
BJ
Chang
Jong-Wook
JW
Yu
Jae-Ran
JR
Koo
Hyun-Sook
HS
Park
Hyun
H
Yoo
Yung Joon
YJ
Ahnn
Joohong
J
D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000378:metabolism*; D037281:Calnexin / Q000737:chemistry* / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006031:Glycosylation; D018869:Heat-Shock Response / Q000502:physiology*; D008969:Molecular Sequence Data; D018384:Oxidative Stress / Q000502:physiology*; D013329:Structure-Activity Relationship
D037281:Calnexin