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Helical Organization of Blood Coagulation Factor VIII on Lipid Nanotubes
12:24

Helical Organization of Blood Coagulation Factor VIII on Lipid Nanotubes

Published on: June 3, 2014

LMAN1 and MCFD2 form a cargo receptor complex and interact with coagulation factor VIII in the early secretory

Bin Zhang1, Randal J Kaufman, David Ginsburg

  • 1Life Sciences Institute, the Departments of Biological Chemistry, Internal Medicine, Human Genetics Howard Hughes Medical Institute, University of Michigan, Ann Arbor, Michigan 48109, USA.

The Journal of Biological Chemistry
|May 12, 2005
PubMed

Insights

LMAN1 and MCFD2 form a complex that binds factor VIII, crucial for preventing combined deficiency of coagulation factors V and VIII. This interaction in the endoplasmic reticulum facilitates proper protein transport.

Area of Science:

  • Molecular Biology
  • Genetics
  • Biochemistry

Background:

  • Mutations in LMAN1 (ERGIC-53) and MCFD2 cause combined deficiency of coagulation factors V and VIII.
  • LMAN1 is a type 1 transmembrane protein, while MCFD2 is a soluble protein interacting with LMAN1 in the endoplasmic reticulum (ER).

Purpose of the Study:

  • To elucidate the interaction mechanism between LMAN1, MCFD2, and coagulation factors V and VIII.
  • To understand the role of LMAN1-MCFD2 complex in the ER-associated transport of coagulation factors.

Main Methods:

  • Cross-linking and immunoprecipitation assays were employed to detect protein interactions.
  • Analysis of protein stoichiometry and dependence on glycosylation and calcium concentration.

Main Results:

  • Endogenous LMAN1 and MCFD2 form a stable 1:1 complex.
  • Both LMAN1 and MCFD2 directly interact with coagulation factor VIII, primarily via its B domain.
  • This interaction is calcium-dependent and independent of factor VIII glycosylation.
  • MCFD2 binding to factor VIII appears independent of the LMAN1-MCFD2 complex.

Conclusions:

  • LMAN1 and MCFD2 function as a cargo receptor complex in the ER.
  • Factor VIII binding is mediated by its B domain through calcium-dependent protein-protein interactions.
  • MCFD2 may specifically recruit factors V and VIII for transport vesicle budding.

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