Cargo selectivity of the ERGIC-53/MCFD2 transport receptor complex.
Exit of soluble secretory proteins from the endoplasmic reticulum (ER) can occur by receptor-mediated export as exemplified by blood coagulation factors V and VIII. Their efficient secretion requires the membrane lectin ER Golgi intermediate compartment protein-53 (ERGIC-53) and its soluble luminal interaction partner multiple coagulation factor deficiency protein 2 (MCFD2), which form a cargo receptor complex in the early secretory pathway. ERGIC-53 also interacts with the two lysosomal glycoproteins cathepsin Z and cathepsin C. Here, we tested the subunit interdependence and cargo selectivity of ERGIC-53 and MCFD2 by short interference RNA-based knockdown. In the absence of ERGIC-53, MCFD2 was secreted, whereas knocking down MCFD2 had no effect on the localization of ERGIC-53. Cargo binding properties of the ERGIC-53/MCFD2 complex were analyzed in vivo using yellow fluorescent protein fragment complementation. We found that MCFD2 is dispensable for the binding of cathepsin Z and cathepsin C to ERGIC-53. The results indicate that ERGIC-53 can bind cargo glycoproteins in an MCFD2-independent fashion and suggest that MCFD2 is a recruitment factor for blood coagulation factors V and VIII.
Nyfeler
Beat
B
Biozentrum, University of Basel, CH-4056 Basel, Switzerland.
Zhang
Bin
B
Ginsburg
David
D
Kaufman
Randal J
RJ
Hauri
Hans-Peter
HP
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D020126:Brefeldin A / Q000494:pharmacology; D020789:Cathepsin C / Q000235:genetics / Q000378:metabolism; D056657:Cathepsin K; D056663:Cathepsin Z; D002403:Cathepsins / Q000235:genetics / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D037241:Mannose-Binding Lectins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D021381:Protein Transport / Q000187:drug effects; D034741:RNA, Small Interfering / Q000235:genetics; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; C084004:LMAN1 protein, human; D008164:Luminescent Proteins; C475146:MCFD2 protein, human; D037241:Mannose-Binding Lectins; D008565:Membrane Proteins; D034741:RNA, Small Interfering; D033921:Vesicular Transport Proteins; C054562:yellow fluorescent protein, Bacteria; D020126:Brefeldin A; D002403:Cathepsins; D020789:Cathepsin C; C534182:CTSZ protein, human; D056663:Cathepsin Z; C534130:CTSK protein, human; D056657:Cathepsin K