The lectin ERGIC-53 is a cargo transport receptor for glycoproteins.
Soluble secretory proteins are transported from the endoplasmic reticulum (ER) to the ER-Golgi intermediate compartment (ERGIC) in vesicles coated with COP-II coat proteins. The sorting of secretory cargo into these vesicles is thought to involve transmembrane cargo-receptor proteins. Here we show that a cathepsin-Z-related glycoprotein binds to the recycling, mannose-specific membrane lectin ERGIC-53. Binding occurs in the ER, is carbohydrate- and calcium-ion-dependent and is affected by untrimmed glucose residues. Binding does not, however, require oligomerization of ERGIC-53, although oligomerization is required for exit of ERGIC-53 from the ER. Dissociation of ERGIC-53 occurs in the ERGIC and is delayed if ERGIC-53 is mislocalized to the ER. These results strongly indicate that ERGIC-53 may function as a receptor facilitating ER-to-ERGIC transport of soluble glycoprotein cargo.
Appenzeller
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C
Department of Pharmacology/Neurobiology, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland.
Andersson
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H
Kappeler
F
F
Hauri
H P
HP
D000595:Amino Acid Sequence; D000818:Animals; D050260:Carbohydrate Metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D056657:Cathepsin K; D056663:Cathepsin Z; D002403:Cathepsins / Q000378:metabolism*; D002460:Cell Line; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006023:Glycoproteins / Q000378:metabolism*; D006801:Humans; D037102:Lectins / Q000235:genetics / Q000378:metabolism*; D037241:Mannose-Binding Lectins; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D011817:Rabbits
D002352:Carrier Proteins; C515307:ERGIC-53 protein, mouse; D006023:Glycoproteins; C084004:LMAN1 protein, human; D037102:Lectins; D037241:Mannose-Binding Lectins; D008565:Membrane Proteins; D002403:Cathepsins; C534182:CTSZ protein, human; D056663:Cathepsin Z; C534184:Ctsz protein, mouse; C534130:CTSK protein, human; D056657:Cathepsin K; C534132:Ctsk protein, mouse