Processing peptidases in mitochondria and chloroplasts

► Most of the organellar proteins are synthesized with N-terminal targeting peptides. ► Targeting peptides are cleaved off inside the organelles by processing peptidases. ► Precursors can be trimmed to increase stability or for intraorganellar routing. ► The cleaved targeting peptides are degraded by the organellar peptidasome, PreP. ► Dysfunctions of processing proteases are associated with human diseases.