Most of the energy that we gain from the breakdown of sugars and other fats is harnessed by mitochondria, the 'power plants' of our cells. However,, specialised cells in some mammals can breakdown fat (‘brown fat’ cells) can release the energy as heat. This type of heat generation is fully reliant on a protein called uncoupling protein 1 (UCP1). UCP1 facilitates the leak of positively charged protons across the inner membrane of mitochondria, which short circuits the conventional proton transport pathway that would otherwise contribute to the production of the nucleotide ATP. The molecular mechanism of UCP1 is not known, but recent research has shown the nucleotide ATP and ADP can bind and regulate the function of UCP1. This proposal aims to improve understanding how ATP/ADP regulation works, by identifying whether the UCP1 conformation changes in the presence of nucleotide.