Prp24: Difference between revisions

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OCA, Kara Perdue, Michal Harel, Alexander Berchansky

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 === Lsm Proteins ===
-The Lsm proteins are a set of seven proteins found in the U6 snRNP that form a ring around the 3' end of U6 (reference Karaduman et al. 2008).  An interaction between Prp24 and the Lsm proteins was suggested upon identification of the Lsms and the fact that formation of U4/U6 by Prp24 was less efficient in deproteinized solutions of U4 and U6 snRNAs (reference Raghunathan and Guthrie), as well as the identification of a genetic interaction between the genes for Prp24 and Lsm4 (Mayes et al. 1999).  This proposed interaction was further supported by UV cross-linking experiments in which both Prp24 and Lsm4 were immunoprecipitated with U6 after cross-linking (reference Vidal et al. 1999).  It has also been shown that both Prp24 and Lsm4, as well as the other Lsm proteins, require the 3' end of U6 in order to interact with the snRNA (Vidal et al. 1999), suggesting that this may be the region where the proteins interact.  Genome-wide protein interaction screens showed that Prp24 interacts additionally with Lsm 2, 5, 6, 7 and 8, and that overexpression of either Prp24 or Lsm4 can complement or intensify the effects of a defect in the other protein (Fromont-Racine et al. 2000), further supporting an interaction between the Lsm proteins and Prp24.
+The Lsm proteins are a set of seven proteins found in the U6 snRNP that form a ring around the 3' end of U6 <ref name="Karaduman2008"/>.  An interaction between Prp24 and the Lsm proteins was suggested upon identification of the Lsms and the fact that formation of U4/U6 by Prp24 was less efficient in deproteinized solutions of U4 and U6 snRNAs <ref name="Raghunathan"/>, as well as the identification of a genetic interaction between the genes for Prp24 and Lsm4 <ref name="Mayes">DOI:10.1093/emboj/18.15.4321</ref>.  This proposed interaction was further supported by UV cross-linking experiments in which both Prp24 and Lsm4 were immunoprecipitated with U6 after cross-linking (reference Vidal et al. 1999).  It has also been shown that both Prp24 and Lsm4, as well as the other Lsm proteins, require the 3' end of U6 in order to interact with the snRNA (Vidal et al. 1999), suggesting that this may be the region where the proteins interact.  Genome-wide protein interaction screens showed that Prp24 interacts additionally with Lsm 2, 5, 6, 7 and 8, and that overexpression of either Prp24 or Lsm4 can complement or intensify the effects of a defect in the other protein (Fromont-Racine et al. 2000), further supporting an interaction between the Lsm proteins and Prp24.
 Evidence for a direct interaction of Prp24 and the Lsm proteins comes from a study in which the conserved residues in the C-terminal domain of Prp24 were deleted, resulting in lowered levels of U4/U6 and very literal interaction with the Lsm proteins as compared to wild-type Prp24, indicating that Prp24 interacts directly with the Lsm proteins and the C-terminal domain is necessary for this interaction (Rader and Guthrie 2002).  Another indication of interaction between Prp24 and the Lsm proteins stems from a study showing that Lsm6 and Lsm7 are necessary in cells that require the recycling of the U4/U6 complex for splicing and that the presence of these two proteins increases the efficiency of annealing of U4 and U6 (Verdone et al. 2004).  This suggests that Lsm6 and 7 are involved in a necessary interaction with Prp24 in the formation of U4/U6 di-snRNP.