Chinese Hamster Ovary K2 Cell Lipid Droplets Appear to be Metabolic Organelles Involved in Membrane Traffic

Pingsheng Liu, Yunshu Ying, Yingming Zhao, Dorothy I. Mundy, Meifang Zhu, Richard G W Anderson

Research output: Contribution to journalArticlepeer-review

411 Scopus citations

Abstract

The principal lipids in animal cell lipid droplets are cholesterol, cholesterol ester, and triglyceride, but the protein composition of this compartment is largely unknown. Here we report on the proteomic analysis of lipid droplets. Using a combination of mass spectrometry and immunoblotting, we identify nearly 40 specifically associated proteins in droplets isolated from Chinese hamster ovary K2 cells grown in normal medium. The proteins fall in to five groups: structural molecules of the droplet-like adipose differentiation-related protein; multiple enzymes involved in the synthesis, storage, utilization, and degradation of cholesterol esters and triglycerides; multiple, different Rab GTPases known to be involved in regulating membrane traffic; signaling molecules such as p50RhoGAP; and a group of proteins that do not fit any classification but include proteins often found in caveolae/rafts such as caveolin-1 and 2 and flotillin-1. The proteome of droplets isolated from cells grown in the presence of oleate is largely the same except for an increase in the amount of adipose differentiation-related protein, caveolin-1, and a protein thought to be involved in phospholipid recycling called CGI-58. Based on the protein profile, the lipid droplet appears to be a complex, metabolically active organelle that is directly involved in membrane traffic and possibly phospholipid recycling. We propose the name adiposome for this organelle.

Original languageEnglish (US)
Pages (from-to)3787-3792
Number of pages6
JournalJournal of Biological Chemistry
Volume279
Issue number5
DOIs
StatePublished - Jan 30 2004

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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