Article

Phosphatidylinositol 4-phosphate formation at ER exit sites regulates ER export.

Department of Cell Biology, University of Pittsburgh School of Medicine, 3500 Terrace Street, Pittsburgh, Pennsylvania 15261, USA.
Developmental Cell (Impact Factor: 10.37). 12/2006; 11(5):671-82. DOI: 10.1016/j.devcel.2006.09.001
Source: PubMed

ABSTRACT The mechanisms that regulate endoplasmic reticulum (ER) exit-site (ERES) assembly and COPII-mediated ER export are currently unknown. We analyzed the role of phosphatidylinositols (PtdIns) in regulating ER export. Utilizing pleckstrin homology domains and a PtdIns phosphatase to specifically sequester or reduce phosphorylated PtdIns levels, we found that PtdIns 4-phosphate (PtsIns4P) is required to promote COPII-mediated ER export. Biochemical and morphological in vitro analysis revealed dynamic and localized PtsIns4P formation at ERES. PtdIns4P was utilized to support Sar1-induced proliferation and constriction of ERES membranes. PtdIns4P also assisted in Sar1-induced COPII nucleation at ERES. Therefore, localized dynamic remodeling of PtdIns marks ERES membranes to regulate COPII-mediated ER export.

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