In all organisms, storage lipids are maintained in the cytoplasm in specialized organelles called lipid droplets (LDs). These structures consist mainly of a core of neutral lipids (triacylglycerols and/or steryl esters) enclosed in a monolayer of phospholipids, and contain a number of proteins which vary considerably with the species. Some structural hydrophobic proteins stabilize the interface between lipid core and cellular aqueous environment. Oleosins are the major proteins of plant LDs, and completely cover the LD surface. Recent studies of this compartment have shown that LDs appear as a complex dynamic organelle. LDs have received a lot of attention as their abnormal dynamics is associated with several diseases (obesity, diabetes, atherosclerosis and myopathies). LDs are also promising sources of lipids for the development of derived products, such as biofuels and alternative molecules for food, medicine and cosmetics. Thus, understanding dynamics of LDs and structure of LD integral proteins is of major importance. We developed a genetic approach using S. cerevisiae to obtain heterologous expression of A. thaliana LD protein: oleosin AtOle1 or caleosin AtClo1. These yeasts overaccumulated LDs leading to a specific increase of storage lipids and these LDs harbor a high level of oleosins. These cells or their purified LDs were exposed to the Soleil synchrotron light (i) to understand the dynamics of lipid storage and carbon fluxes by measuring the biochemical changes on single cells using the sFTIR microspectroscopy, (ii) to obtain structural data on whole cellular organelle and on oleosins inserted in LD using SRCD, Deep UV imaging and Synchrotron water radiolysis footprinting of accessible oleosin amino-acids.