Gene Expression Regulation: mRNA Processing and Nuclear Transport Control

What are the 2 types of control of gene regulation at mRNA processing and nuclear transport processes?

• Post transcriptional mechanisms

• Regulation of mRNA degradation

What is mRNA processing and nuclear transport control?

• Controlling how pre-mRNE is spliced or processed

• Some RNAs are selectively transported to cytoplasm

Post transcriptional mechanisms

Effect on gene expression

Types

Effect on gene expression: It may be blocked or stimulated

Types:

• Addition of 5’ cap

• 3’ cleavage and addition of poly(A) tail

• RNA splicing

• Alternative RNA splicing

  • When different mRNA molecules produced from same primary transcript

• RNA editing

Regulation of mRNA degradation

When are prokaryotic mRNA molecules degraded

When are eukaryotic mRNA molecules degraded

Common pathway of mRNA breakdown (3)

When are prokaryotic mRNA molecules degraded: Only after a few minutes

When are eukaryotic mRNA molecules degraded: After few days or weeks

Common pathway of mRNA breakdown: Begins with enzymatic shortening of poly(A) tail

• This triggers enzymatic removal of 5’ cap

• Followed by rapid degradation by nucleases