Sandbox WWC7: Difference between revisions

Pentatricopeptide repeat (PPR) proteins are a family of sequence specific RNA-binding proteins which participate in organelle RNA metabolism. Although the mechanisms of RNA binding and the functions of PPR proteins are not fully understood, PPR proteins are thought to assist in RNA editing,<ref>PMID:17015439</ref> translation,<ref name = "translation">DOI:10.1073/pnas.1012076108</ref> and organelle biogenesis.<ref>PMID:15269332</ref> While PPR proteins are found in many eukaryotes, most known PPR proteins are found in plants, and they make up the majority of RNA-binding factors in plant organelles. PPR proteins are characterized by a series of tandem-repeat amino acid consensus sequences which form α-helix <scene name='69/696301/Hairpins/1'>hairpins</scene>. These hairpin structures accumulate to form an <scene name='69/696301/Monomer/1'>α-solenoid tertiary structure</scene> (blue to red from N terminus to C terminus). PPR proteins belong to one of two classes: P-class and PLS-class, with the P-class containing 35 amino acid repeats and the PLS-class containing 31–36 amino acid repeats. P-class PPR proteins generally bind irreversibly to non-coding regions of RNA, whereas PLS-class PPR proteins bind reversibly to coding regions. PPR10 (shown to the right dimerized and bound to RNA) is a well-characterized P-class PPR protein found in the chloroplast of ''Zea mays'' which is often used as a model PPR protein.<ref name = "translation"/>