BIOL 4610: Post Transcriptional Regulation

Translational regulation

Control of protein production; involves pre-mRNA processing, miRNAs, siRNAs, and mRNA localization

Pre-mRNA

Contains introns and needs a few modifcaitons

Steps to produce a mature mRNA

• 5’ capping

• 3’ poly-A tail

• Splicing

5’ capping

• Addition of 7-methylguanosine and several phosphates

• RNA nucleotides of pre-mRNA are methylated

• Prevents degradation of pre-mRNA by exonucleases

Polyadenylation

• Multiple adenines are added to the 3’ end

• The 3’ end of is activated by an enzyme to produce a poly-A tail

Splicing

Spliceosomes

Carry out splicing; composed of small nuclear RNAs

snRNPs

snRNAs and their associated proteins

lncRNAs

Bind to exons and prevent their integration into the mature mRNAs

miRNAs

Short segments of RNA; transcribed similar to protein coding genes; once processed, it becomes a short, double-stranded duplex; guides RISC to target mRNAs

If the miRNA has perfect complementation to the target mRNA, __

The RISC complex will promote the degradation of that mRNA

If the miRNA has some complementation to the target mRNA, __

Translation by the ribosome will be blocked

More than __ of human gene expression is regulated by miRNAs

60%

miRNA production allows for __

Fine-tuning of gene expression and make sure the correct amount of protein is made

__ recognize sequences on the ends of introns

U1 and U2

snRNPs work with U1 and U2 to bring both ends of the intron together to form a __ and splice out the intron

Lariat

The looped out intron is degraded by the __

Exosome