Figure 1.

Roles for pentatricopeptide (PPR) proteins in mitochondrial gene expression.

PPR proteins have been found associated with every known stage of gene expression between transcription and translation. 1: PPR proteins have been found associated with the mitochondrial RNA polymerase; 2: PPR proteins have been implicated in RNA cleavage; 3: PPR proteins have been implicated in splicing; 4: PPR proteins have been implicated in editing; 5: PPR proteins are strongly thought to play a role in translation initiation; 6: PPR proteins are thought to be associated with ribosomes and to in some cases to tether the translation machinery to the mitochondrial inner membrane to facilitate insertion of newly synthesized polypeptides into the correct complex. Figure reproduced from Andres et al. (2007).