In the yeast Saccharomyces cerevisiae as in other eukaryotes non-polar lipids are a reservoir of energy and
building blocks for membrane lipid synthesis. The yeast non-polar lipids, triacylglycerols (TG) and steryl
esters (SE) are stored in so-called lipid particles/droplets (LP) as biologically inert form of fatty acids and
sterols. To understand LP structure and function in more detail we investigated the molecular equipment of
this compartment making use of mass spectrometric analysis of lipids (TG, SE, phospholipids) and proteins.
We addressed the question whether or not lipid and protein composition of LP influence each other and
performed analyses of LP from cells grown on two different carbon sources, glucose and oleate. Growth of cells
on oleate caused dramatic cellular changes including accumulation of TG at the expense of SE, enhanced the
amount of glycerophospholipids and strongly increased the degree of unsaturation in all lipid classes. Most
interestingly, oleate as a carbon source led to adaptation of the LP proteome resulting in the appearance of
several novel LP proteins. Localization of these new LP proteins was confirmed by cell fractionation.
Proteomes of LP variants from cells grown on glucose or oleate, respectively, were compared and are
discussed with emphasis on the different groups of proteins detected through this analysis. In summary, we
demonstrate