mRNA splicing and processing

Question 1

PARPs

Answer 1

• polyadenylation recognition proteins
• protect against 3’ -> 5’ nucleases
• docking sites
• auxiliary factor recognition
• co-oopted for PCR

Question 2

cap

Answer 2

complex for ribosome assembly

Question 3

5’ modification

Answer 3

1. 5’PPP of 1st nt = dephosphorylated
2. N7 methylation
3. OH2 ribose methylation downstream
4. increase hydrophobicity

Question 4

How are splice sites paired?

Answer 4

• phosphorylated RNAPII catalytic site C terminal recruits splicing regulation

Question 5

cryoEM shows

Answer 5

co-transcriptional splicing

Question 6

generating cDNA from mRNA + RNA quantification in PCR

Answer 6

1. poly-t primer
2. RT
3. ligate

Question 7

spliceosome assembly

Answer 7

1. U2AF binds 3’ splice site and polypyrimidine tract
2. U2 binds internal branch site

Question 8

spliceosome

Answer 8

• 5 snRP
• 41 associated

Question 9

Transesterification

Answer 9

1. Branch site 2’A OH- attacks 5’ site nucleophilically (U2-U6 alignment)
2. U5 loop alignes 2nd transesterification

Question 10

lariat intron

Answer 10

debranched for regulation or exonuclease degradation

Question 11

SR proteins

Answer 11

• U1-U2 connection
• different families: plant-specific, SCL, two-Zn-knuckle type

Question 12

exon definition proteins

Answer 12

• prevent U1-U2 connection
• flanking intron excision

Question 13

circRNAs

Answer 13

• protein enhancers
• translation templates (peptides)

Question 14

alternative spicing

Answer 14

• mutually exclusive exons
• combinatorial exon selection
• alternative promotor splicing