The mitochondrion is generally recognized to have been once a free-living aerobic organism, which became an intracellular resident of another primorida, probably anaerobic organism. Indisputedly necessary for the origin of multicellularity, the mitochondrion eventually was freed of the need to possess an entire repertoire of genetic information. Through the evolution of systems to enable the promitochondrion to import proteins from the surrounding cytoplasm, and with the consequent or concurrent mutational inactivation or loss of functional genes, the mitochondrion realized a drastic reduction in the coding capacity of its genome. In most animals the mitochondrial genome now encodes only 13 proteins of the thousands necessary for its biogenesis and functions. All 13 are inner membrane proteins and involved in the electron transport chain or ATPase. Due to the centralized role of the mitochondrion in the life of the cell, indeed, of multicellular life itself, we are initiating this data base to provide a centralized bibliographic depository of genetic information about the mitochondrion.
The mammalian mitochondrion serves as the focal point, initially the database concentrates on human, mouse, and rat nuclear gene products imported into the mitochondrion, although we are including yeast and other fungal mitochondrial systems, as well as plant mitochondrial systems. We have maintained the natural classification system embodied in mitochondrial compartmentalization; the outer membrane, intermembrane space, inner membrane, and matrix, with further demarcation into enzyme systems and enzyme complexes.
The user is encouraged to contact the editor-in-chief with corrections, preprints, reprints, and other information related to mitochondrial proteins to be included in this database.