Mid 2: Lec 10

Question 1

mirna transcription and characteristics

Answer 1

primary miRNA (pri-mirna) typically transcribed by RNA Pol II

can be coding

miRNA loci often polycistronic

Question 2

Microprocesser complex inc cofactors and transport

Answer 2

converts pri-mirna to pre-mirna

drosha is the endonuclease

dgcr8 is an essential cofactor

pre mirnas exported to cytoplasm by exportin 5

Question 3

pre-mirna processing inc cofactors

Answer 3

dicer is the endonuclease

trbp and pact are cofactors

Question 4

RISC assembly and general function

Answer 4

rna induced silencing complex

1. loading of miRNA duplex into argo protein
   2.unwinding

loads siRNAs and miRNAs
scans mrnas in cell for complementarity and facilitates silencing

Question 5

Argonaute domains and functions

Answer 5

MID binds 5’ phosphate, binds 5’ most nts

PIWI binds 5’ most nts, carries out slicer activity

PAZ binds 3’ end

Cleft for mRNA

Question 6

GW182 proteins

Answer 6

interact with and act downstream of agos

GW182 tethers to mrna and leads to translational suppression and mrna stabilization

Question 7

decapping and deadenylation

Answer 7

1. risc complex does deadenalation: gw182 and caf1 and ccr4
2. DCP1/DCP2 does decapping
3. decay of mrna

Question 8

processing bodies

Answer 8

gel like regions, not organelles

deadenylation, decapping, degradation of mrnas