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Kinase signaling initiates coat complex II (COPII) recruitment and export from the mammalian endoplasmic reticulum

M Aridor1, W E Balch

  • 1Departments of Cell and Molecular Biology and the Institute for Childhood and Neglected Diseases, The Scripps Research Institute, La Jolla, California 92037, USA.

The Journal of Biological Chemistry
|September 26, 2000
PubMed

Insights

Kinase regulation is essential for endoplasmic reticulum (ER) export. A specific inhibitor blocks Sar1 recruitment, preventing coat complex II (COPII) vesicle formation and cargo export from the ER.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Coat Complex II (COPII) mediated vesicle formation is critical for protein and lipid export from the endoplasmic reticulum (ER).
  • The precise regulatory mechanisms governing COPII assembly and ER export remain incompletely understood.
  • Activation of the small GTPase Sar1 initiates COPII recruitment to ER exit sites.

Purpose of the Study:

  • To investigate the potential role of kinase regulation in the initiation of COPII vesicle formation.
  • To elucidate the molecular events underlying Sar1 recruitment and COPII polymerization.

Main Methods:

  • Utilized purified COPII components in in vitro membrane recruitment assays.
  • Employed cargo export assays to assess functional consequences of inhibited COPII formation.
  • Investigated the effect of the serine/threonine kinase inhibitor H89 on Sar1 and COPII component recruitment.

Main Results:

  • Sar1 recruitment to ER membranes necessitates ATP hydrolysis.
  • The kinase inhibitor H89 effectively blocked Sar1 membrane recruitment.
  • Inhibition of Sar1 recruitment prevented COPII coat polymerization and subsequent ER export of cargo.

Conclusions:

  • ER export and COPII vesicle formation initiation in mammalian cells are regulated by kinase activity.
  • Kinase-dependent regulation of Sar1 GTPase is a key step in initiating the ER export pathway.

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