Prp24: Difference between revisions

Pre-mRNA splicing is an essential process in eukaryotes that removes non-coding introns from a pre-mRNA transcript and splices coding exons together before the mRNA is exported from the nucleus for translation into a protein<ref name="Staley">PMID:9476892</ref>.  Splicing requires five snRNPs (U1, U2, U4, U5, U6), several other proteins, and the input of energy from ATP.  The U1 and U2 snRNPs assemble individually on the pre-mRNA transcript, while U4 and U6 form a U4/U6 di-snRNP before interacting with U5 to form a U4/U6.U5 tri-snRNP that combines with U1 and U2 at the pre-mRNA transcript<ref name="Staley"/>.  U4 and U1 then depart, and after conformational changes and base pair formation with the pre-mRNA the remaining snRNPs form the catalytically active spliceosome<ref name="Staley"/>.  Two transesterification reactions then occur; the first reaction is the nucleophillic attack of the a phosphate group at the end of the 5' exon by the 2' hydroxyl of a specific adenosine at the branch point sequence of the intron<ref name="Brow review">PMID:12429696</ref>.  This is then followed by the nucleophillic attack of the phosphorous group linking the 3' exon to the intron by the 3' hydroxyl of the 5' exon<ref name="Brow review"/>.  These splicing reactions, in addition to the addition of 7-methylguanosine 5' cap and  a 3' polyadenosine tail, results in a mature mRNA transcript that can be exported from the nucleus and translated into protein.

===U6 and U4 snRNPs===