mRNA Stability Flashcards

Flashcards to review mRNA stability concepts from BIO 330 lecture.

3′ untranslated region (UTR)

The untranslated sequence downstream from the coding region of an mRNA.

5′ untranslated region (UTR)

The untranslated sequence upstream from the coding region of an mRNA.

Stem-loop

A secondary structure that appears in RNAs consisting of a base-paired region (stem) and a terminal loop of single-stranded RNA.

Endoribonuclease

A ribonuclease that cleaves an RNA at an internal site(s).

Exoribonuclease

A ribonuclease that removes terminal ribonucleotides from RNA.

Processive (exonuclease)

An enzyme that remains associated with the substrate while catalyzing the sequential removal of nucleotides.

Distributive (exonuclease)

An enzyme that catalyzes the removal of only one or a few nucleotides before dissociating from the substrate.

mRNA decay

mRNA degradation

Steady state (molecular concentration)

The concentration of population of molecules when the rates of synthesis and degradation are constant.

mRNPs

mRNA-protein complexes.

Polyribosome (or polysome)

An mRNA that is simultaneously being translated by multiple ribosomes.

Monocistronic mRNA

mRNA that codes for one polypeptide.

Poly(A) polymerase (PAP)

The enzyme that adds the stretch of polyadenylic acid to the 3′ end of eukaryotic mRNA; it does not use a template.

Poly(A) binding protein (PABP)

The protein that binds to the 3′ stretch of poly(A) on a eukaryotic mRNA protects the tail initially

Cytoplasmic cap-binding protein

Protects the cap from decapping until translation initiation.

mRNA-Specific Half-Lives

Specific cis-elements in an mRNA affect its rate of degradation.

Destabilizing elements (DEs)

Can accelerate mRNA decay

Stabilizing elements (SEs)

Can reduce mRNA decay.

Iron-response element (IRE)

A cis sequence found in certain mRNAs whose stability or translation is regulated by cellular iron concentration.

Release factor (RF)

A protein required to terminate polypeptide translation to cause release of the completed polypeptide chain and the ribosome from mRNA.

Nonsense-mediated decay (NMD)

Targets mRNAs with premature stop codons.

Nonstop decay (NSD)

Targets mRNAs lacking an in-frame termination codon and requires a conserved set of SKI proteins.

No-go decay (NGD)

Targets mRNAs with stalled ribosomes in their coding regions.

RNA granules

Are formed by aggregation of translationally silenced mRNA and many different proteins.

Zipcode (or localization signal)

Any of the number of mRNA cis elements involved in directing cellular localization.