| Type: | Repeat | Name: | Pentatricopeptide repeat |
| Description: | This entry represents the PPR repeat.Pentatricopeptide repeat (PPR) proteins are characterised by tandem repeats of a degenerate 35 amino acid motif []. Most of PPR proteins have roles in mitochondria or plastid []. PPR repeats were discovered while screening Arabidopsis proteins for those predicted to be targeted to mitochondria or chloroplast [, ]. Some of these proteins have been shown to play a role in post-transcriptional processes within organelles and they are thought to be sequence-specific RNA-binding proteins [, , ]. Plant genomes have between one hundred to five hundred PPR genes per genome whereas non-plant genomes encode two to six PPR proteins.Although no PPR structures are yet known, the motif is predicted to fold into a helix-turn-helix structure similar to those found in the tetratricopeptide repeat (TPR) family (see ) []. The plant PPR protein family has been divided in two subfamilies on the basis of their motif content and organisation [, ].Examples of PPR repeat-containing proteins include PET309 , which may be involved in RNA stabilisation [], and crp1, which is involved in RNA processing []. The repeat is associated with a predicted plant protein that has a domain organisation similar to the human BRCA1 protein. | Short Name: | Pentatricopeptide_repeat |
