Stamm 3-30 mRNA splicing

Question 1

Sequences needed for splicing

Answer 1

GU at the 5’ splice site (nomenclature based on intron), AG at 3’ splice site, A branch site pyrimidine run before 3’ splice site

Question 2

exon definition model

Answer 2

regulation through combinatorial control- where the ESE (exonic spicing enhancer) bind SR proteins (rich in Serine Arginine sequences) and interact with U1 at the GU and U2 at the A branch site

Question 3

steps of splicing pre-mRNA

Answer 3

2 transesterification: 2’OH of branch site A does nucleophilic attack on the G of the 5’splice site to make lariat, then exon at 5’ splice site does 3’OH :Nu attack on the 3’ splice site to join the exons

Question 4

What segment makes up the majority of pre-mRNA

Answer 4

introns