Transcriptional Regulation in Eukaryotes pt. 2

Alternative splicing

Multiple transcripts from 1 pre-mRNA

Deadenylation-dependent mRNA decay

Degrades most eukaryotic mRNAs

Deadenylase enzyme

Shortens poly-A tail to less than 30 nucleotides

Function of nonsense-mediated decary

Degrade mRNA if a premature stop codon is detected by the cell

Two types of RNA interference (RNAi)

microRNA and small interfering RNA

Function of precursor miRNA

Single strand folded on itself to be double-stranded

RISC complex

Takes one strand of the miRNA/siRNA and carries it around, looking for complementary mRNA

Functions of long mRNA

Scaffold, bind to DNA and bring chromatin modifying complexes, act as a decoy and binds along non-coding mRNA or binds to transcription factor

Scaffold

Helps different protein complexes to come together

Types of post-transcriptional modifications

Cleavage, addition of chemical groups, ubiquitylation

Cleavage

Cuts the protein

Example of cleavage

Pro-insulin is cleaved to make insulin

Examples of addition of chemical groups

Histone modifications, phosphorylation

Ubiquitylation

Ubiquitin peptides can be added to proteins; effect based on number of ubiquitin units added

Function of poly-Ub tag

Targets the protein for degradation via the proteasome