Director, Mass Spectrometry LaboratoryDepartment of Biochemistry and Molecular Biology
University of Kansas Medical Center
(913) 588-3487
aartigues@kumc.edu
Newly made proteins must achieve their native configuration before they can play their physiological roles in the cell. These processes are of particular importance for mitochondria. Of the roughly 1100 different proteins present in the mitochondrion only 13 are encoded by the mitochondrial DNA and synthesized in the mitochondrial matrix. The remaining proteins are encoded by the nuclear genome, transcribed in the nucleus, translated in the cytoplasm and imported into the mitochondrion, where they fold to their native structure. Understanding these processes at the molecular level is of the utmost importance because alterations in protein folding or mitochondrial protein translocation cause disease.
The model system used to study this process is the eukaryotic isoenzymes of aspartate aminotransferase. Two isoenzymes, one cytosolic, the other mitochondrial, exist in all eukaryotic cells. These proteins have extensive amino acid similarity, an almost identical three dimensional structure, are encoded by the genomic DNA, and are synthesized in the cytoplasm. Despite these similarities the mature proteins have different folding kinetics and different sub-cellular locations. Our main goals are to understand; (a) the molecular basis for the distinct folding behavior of these homologous proteins, and (b) to elucidate the mechanisms for the differences observed in their interactions with the cellular machineries in charge of protein sorting, import and folding.
