Turnover and degradation of mitochondria and their proteins.

Very little is known about intracellular protein degradation. We have concentrated on mitochondrial proteins for simplicity. Even this is a complex problem and several mechanisms may be involved. The half-lives of mitochondrial proteins vary widely. Using immunological, autoradiographic (ferritin and iodine) and biochemical techniques we are delineating the extent of intra-mitochondrial protein degradation, lysosomal participation in that degradation, and signals controlling the overall process. As a high yielding dividend of our autoradiographic and immunological experiments it seems possible to clarify such important questions as whether there is a selective inactivation and turnover of mitochondria and their proteins. Calculations of autophagy and vacuoles, the concentration of mitochondrial proteins within lysosomes, as well as key aspects of the initiation and regulation of protein turnover and its elasto-plastic control are presented.