Most mature proteins do not retain their initial N-terminal amino acid (methionine in the cytosol and N-formyl methionine in the organelles). Recent studies have shown that dedicated machinery is involved in this process in plants. In addition to cytosolic and organelle-targeted methionine aminopeptidases, organellar peptide deformylases have been identified. Here, we attempt to answer questions about the mechanism, specificity and significance of N-terminal methionine cleavage in plant organelles. It seems to be universal because orthologues of plant deformylases are found in most living organisms.