Prp24: Difference between revisions

Prp24 is a U6 snNRP protein that functions in the annealing of the U4 and U6 snRNPs during the assembly of the spliceosome.  This protein was first identified in a genetic screen as mutated gene that caused an accumulation of pre-mRNA <ref name="Vij">PMID:2676722</ref>.  It's first functional role was suggested after several mutant forms of the protein were found to suppress a cold sensitive growth defect caused by mutations in the U4 snRNA <ref name="Shannon">PMID:1827420</ref>.  It is thought that Prp24 helps to stabilize the U6 snRNA and hold it in a conformation that promotes base pairing interactions with the U4 snRNA to form the stem I and stem II structures of the U4/U6 di-snRNP.  Prp24 departs from the U4/U6 complex before the formation of the U4/U6.U5 tri-snRNP, but it has been suggested that Prp24 may also play a role in the dissociation of U4 from U6 during the base pairing of U6 with U2 and the 5' splice site <ref name="Vaidya">Vaidya V, Vijayraghavan U. Prp21, a U2-snRNP-associated protein, and Prp24, a U6-snRNP-associated protein, functionally interact during spliceosome assembly.  J Genet. 1998 Dec; 77(3):85-94</ref>.  This additional role for Prp24, however, has not been experimentally supported.       

The key structural elements of Prp24 are the conserved RNA recognition motifs (RRMs).  These motifs are found in many proteins with RNA binding properties and are contain conserved RNP elements that are recognizable from their primary sequence.  For several years, Prp24 was thought to contain three RRMs, termed RRM 1, RRM 2, and RRM 3 (green link)(reference Shannon and Guthrie 1991).  However, analysis of homologs of Prp24 from several different species allowed the identification of a fourth RRM in Prp24 of ''S. cerevisiae'', albeit one that was much less highly conserved and not easily recognizable by its RNP-consensus domain (reference Rader and Guthrie 2002).