Regulation of oxysterol-binding protein Golgi localization through protein kinase D-mediated phosphorylation

Sokha Nhek, Mike Ngo, Xuemei Yang, Michelle M. Ng, Seth J. Field, John M. Asara, Neale D. Ridgway, Alex Toker

Research output: Contribution to journalArticlepeer-review

99 Citations (Scopus)

Abstract

Protein kinase D (PKD) plays a critical role at the trans-Golgi network by regulating the fission of transport carriers destined for the plasma membrane. Two known Golgi-localized PKD substrates, PI4-kinase IIIβ and the ceramide transfer protein CERT, mediate PKD signaling to influence vesicle trafficking to the plasma membrane and sphingomyelin synthesis, respectively. PKD is recruited and activated at the Golgi through interaction with diacylglycerol, a pool of which is generated as a by-product of sphingomyelin synthesis from ceramide. Here we identify a novel substrate of PKD at the Golgi, the oxysterol-binding protein OSBP. Using a substrate-directed phospho-specific antibody that recognizes the optimal PKD consensus motif, we show that PKD phosphorylates OSBP at Ser240 in vitro and in cells. We further show that OSBP phosphorylation occurs at the Golgi. Phosphorylation of OSBP by PKD does not modulate dimerization, sterol binding, or affinity for PI(4)P. Instead, phosphorylation attenuates OSBP Golgi localization in response to 25-hydroxycholesterol and cholesterol depletion, impairs CERT Golgi localization, and promotes Golgi fragmentation.

Original languageEnglish
Pages (from-to)2327-2337
Number of pages11
JournalMolecular Biology of the Cell
Volume21
Issue number13
DOIs
Publication statusPublished - Jul 1 2010

ASJC Scopus Subject Areas

  • Molecular Biology
  • Cell Biology

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