- Pentatricopeptide Repeat Protein
Pentatricopeptide Repeat (PPR) proteins are a family of
proteins commonly found in theplant kingdom. They are distinguished by their repeating 35-amino acid motif [cite web | author= | title=Identification of pentatricopeptide repeat proteins in Trypanosoma brucei | url=http://mcdb.colorado.edu/postdoctoral/postdocpublications/clementslpublications/Identification-of-pentatricopeptide-repeat-proteins-in-Trypanosoma-brucei | date= 01 November 2006 | publisher=Molecular and biochemical parasitology | accessdate=2008-08-08] , and by their relative lack ofintrons Fact|date=December 2007.Approximately 450 such proteins have been identified in the
arabidopsis genome, and another 477 in therice genome [cite web | author= Nicholas O'Tool et al | title=On the Expansion of the Pentatricopeptide Repeat Gene Family in Plants | url=http://mbe.oxfordjournals.org/cgi/content/abstract/25/6/1120 | date= 14 March 2008 | publisher=Molecular Biology and Evolution | accessdate=2008-08-08] .The purpose of PPR proteins is currently under dispute. It has been shown that a good deal of those in Arabidopsis interact (often essentially) with
mitochondria and otherorganelles [cite web | author= Claire Lurin et al | title=Genome-Wide Analysis of Arabidopsis Pentatricopeptide Repeat Proteins Reveals Their Essential Role in Organelle Biogenesis | url=http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=519200 | date= 22 April 2004 | publisher=American Society of Plant Biologists | accessdate=2008-08-08] and that they are possibly involved in editingRNA . However many trans proteins are required for this editing to occur and research continues to look at which proteins are needed. [ibid]Footnotes
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