LIFESCI 3 Lecture Notes - Lecture 12: Precursor Mrna, Exonuclease, Methyl Group
Document Summary
Splice out intron before transportation out to the cytoplasm mrna associated w/ ribosomes much smaller than pre-mrna (with introns) hnrna. Protein around pre-mrna that associates w/ other proteins. Rna processing - 5" cap, splicing, 3" poly a tail. Splicing proteins, 3" end processing protein binds to ctd domain of rpb1. 5" to 5" triphosphate bridge w/ 7-methylguanylate (gtp residue) Methyl group is added to ribose sugar on some caps. Need to recognize 5" cap for translation to begin. Spliceosome snrnas (small nuclear) and snrnps (small nuclear ribonucleoproteins) Complementary sequence w/ rna snrnas recog 5" splice site, 3" splice site, branch-point site thru base-pairing. U1 leaves after rearrangement w/ atp, u6 enters to remove intron. Attacks 5" splice site, attaches to 5" p of intron, frees 3" oh of exon 1 end. 3" oh of exon 1 attacks 3" splice site (of intron), frees exon 2. Same pre-mrna can be spliced into different mrna.
