In BAT, mitochondria and LDs form extensive contact sites to orchestrate lipid metabolism. To date, the LD-mitochondrial contact site proteome, its dynamics and regulation remains elusive. We established an organelle proteomics workflow to generate a global map of protein expression, modification and localization upon induction of thermogenesis. We will combine proteomics with cryo-electron tomography and super-resolution microscopy to study the architecture of these contact sites. Combining state-of-the-art techniques, this project will unravel the organelle proteomes and enable studies on dynamic organelle interaction in BAT.