Repeat

Pentatricopeptide repeat (IPR002885)

Short 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 [PMID: 10664580]. Most of PPR proteins have roles in mitochondria or plastid [PMID: 15270678]. PPR repeats were discovered while screening Arabidopsis proteins for those predicted to be targeted to mitochondria or chloroplast [PMID: 10664580, PMID: 15269332]. 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 [PMID: 12782738, PMID: 12832482, PMID: 18031283]. 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 PDOC50005) [PMID: 10664580].

The plant PPR protein family has been divided in two subfamilies on the basis of their motif content and organisation [PMID: 15269332, PMID: 17560114].

Examples of PPR repeat-containing proteins include PET309 P32522, which may be involved in RNA stabilisation [PMID: 7664742], and crp1, which is involved in RNA processing [PMID: 8039510]. The repeat is associated with a predicted plant protein O49549 that has a domain organisation similar to the human BRCA1 protein.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE profiles
Pfam
Pfam
TIGRFAMs
Pfam
Pfam