The ADP/ATP carrier protein (AAC), the most common protein on the inner mitochondrial membrane, controls the exchange of ADP from the cytosol with ATP produced in the matrix. Expressed in the cytosol, AAC relies on a succession of mitochondrial translocases for import across the outer membrane and insertion into the inner membrane. To interact with these translocases, AAC contains localisation information in the form of multiple permanent internal targeting sequences. These are located around its six hydrophobic transmembrane α-helices. At the outer membrane these sequences are first bound by Translocase of the outer Membrane Tom70, and in yeast its homologue Tom71. Tom70/71 contains a large cytosolic domain bearing a large hydrophobic binding pocket. This binds AAC, which is then transferred to downstream components of the TOM pathway. Our aim to further characterise the interaction between Tom70/71 and AAC. This is being accomplished using synthetic peptides corresponding to the transmembrane binding sites of AAC. Fluorescence anisotropy and isothermal titration calorimetry binding assays are being used to characterise their affinity for Tom70/71. Single site mutagenesis is being used on Tom71 to attempt to inhibit the binding of AAC and determine the specific residues involved in their interaction. Small angle X-ray scattering is used to characterise any structural changes to Tom70/71 upon AAC binding. Attempts are also being made to co-crystallise Tom71 and AAC for X-ray crystallography, to visualise their interaction.