Phosphatidylinositol-4-kinase type II α is a component of adaptor protein-3-derived vesicles

Gloria Salazar, Branch Craige, Bruce H. Wainer, Jim Guo, Pietro De Camilli, Victor Faundez

Research output: Contribution to journalArticlepeer-review

91 Scopus citations

Abstract

A membrane fraction enriched in vesicles containing the adaptor protein (AP)-3 cargo zinc transporter 3 was generated from PC12 cells and was used to identify new components of these organelles by mass spectrometry. Proteins prominently represented in the fraction included AP-3 subunits, synaptic vesicle proteins, and lysosomal proteins known to be sorted in an AP-3-dependent way or to interact genetically with AP-3. A protein enriched in this fraction was phosphatidylinositol-4-kinase type IIα (PI4KIIα). Biochemical, pharmacological, and morphological analyses supported the presence of PI4KIIα in AP-3-positive organelles. Furthermore, the subcellular localization of PI4KIIα was altered in cells from AP-3-deficient mocha mutant mice. The PI4KIIα normally present both in perinuclear and peripheral organelles was substantially decreased in the peripheral membranes of AP-3-deficient mocha fibroblasts. In addition, as is the case for other proteins sorted in an AP-3-dependent way, PI4KIIα content was strongly reduced in nerve terminals of mocha hippocampal mossy fibers. The functional relationship between AP-3 and PI4KIIα was further explored by PI4KIIα knockdown experiments. Reduction of the cellular content of PI4KIIα strongly decreased the punctate distribution of AP-3 observed in PC12 cells. These results indicate that PI4KIIα is present on AP-3 organelles where it regulates AP-3 function.

Original languageEnglish
Pages (from-to)3692-3704
Number of pages13
JournalMolecular biology of the cell
Volume16
Issue number8
DOIs
StatePublished - Aug 2005

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