Cargo selectivity of the ERGIC-53/MCFD2 transport receptor complex

Traffic. 2006 Nov;7(11):1473-81. doi: 10.1111/j.1600-0854.2006.00483.x. Epub 2006 Oct 1.

Abstract

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Brefeldin A / pharmacology
  • Cathepsin C / genetics
  • Cathepsin C / metabolism
  • Cathepsin K
  • Cathepsin Z
  • Cathepsins / genetics
  • Cathepsins / metabolism
  • Endoplasmic Reticulum / metabolism
  • HeLa Cells
  • Humans
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Mannose-Binding Lectins / genetics
  • Mannose-Binding Lectins / metabolism*
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Protein Binding
  • Protein Interaction Mapping
  • Protein Transport / drug effects
  • RNA, Small Interfering / genetics
  • Vesicular Transport Proteins / genetics
  • Vesicular Transport Proteins / metabolism*

Substances

  • Bacterial Proteins
  • LMAN1 protein, human
  • Luminescent Proteins
  • MCFD2 protein, human
  • Mannose-Binding Lectins
  • Membrane Proteins
  • RNA, Small Interfering
  • Vesicular Transport Proteins
  • yellow fluorescent protein, Bacteria
  • Brefeldin A
  • Cathepsins
  • Cathepsin C
  • CTSZ protein, human
  • Cathepsin Z
  • CTSK protein, human
  • Cathepsin K