Biochemistry 2280A Lecture Notes - Lecture 25: Glutamine, Antibiotics, Ribosome
Document Summary
Topic 23: rna processing in eukaryotic cells: 5" capping. You have a triphosphate at the 5" end this is coupled in a linkage to 7- methylguanosine (unique 5"-5" linkage) This is done as soon as the 5" end of the rna is exposed. This marks the 5" end as being intact and useable important for mrna export from the nucleus and translation of the mrna: 3" polyadenylation (polya tail) Poly a tail is at the 3" end. There"s a stop codon after that, there"s an aauaa signal which is the signal for the polyadenylation machinery to come in and clip the rna downstream from that signal sequence. After it clips adds polya tail along the 3" end of rna. This marks the 3" end as being intact for mrna export and translation. Poly-a tail also protect mrna from degradation from exonucleases. An intact mrna must have an 5" cap and 3" polya tail: rna splicing.