Maintenance of correct mitochondrial metabolism requires the coordinated and regulated transport of metabolites between the cytosol and the matrix. This process is mediated by carrier proteins, which facilitate exchange of metabolites across the mitochondrial inner membrane. Biogenesis of mitochondrial carrier proteins requires an import complex known as the Translocase of the Inner Membrane 22 (TIM22 complex). Recent study of the human TIM22 complex revealed the presence of a novel subunit, acylglycerol kinase (AGK), a protein which had previously been characterised as a lipid kinase. Mutations in AGK are also known to cause Sengers syndrome, a rare and severe mitochondrial disease characterised by hypertrophic cardiomyopathy, lactic acidosis, exercise intolerance, and congenital cataracts. The disease displays significant phenotypic diversity, and it is not known whether pathogenesis arises predominantly due to loss of the proteins lipid kinase activity, protein import activity, or indeed both. I have studied fibroblasts from several Sengers patients in to understand how mutations in AGK effect the function of the protein and cause disease, with a particular interest in understanding how the two distinct functions of AGK contribute differently to disease when impaired. We have also employed proteomics approaches to characterise changes that occur to the mitochondrial proteome during Sengers syndrome.