Cleavage-Sites in Protein Targeting Signals

Proteins in both prokaryotic and eukaryotic cells have to find their way among a plethora of subcellular compartments. The targeting information in most cases resides in distinct stretches of amino acids or targeting peptides (TPs). The sequence characteristics of a number of different TPs have been defined by comparative sequence analysis and experimental studies. TPs targeting proteins for secretion, for import into mitochondria, and for import into chloroplasts will be reviewed, with particular emphasis on the patterns of amino acids that define their cleavage sites.