Inhibins and activins are members of the TGFβ superfamily

TLS Online TPP Program

#Id: 6762

#Unit 3. Fundamental Processes

The exposed cap is then removed by a decapping enzyme (DCP1/DCP2), unprotected mRNA susceptible to degradation by XRN1, a 5′→3′ exoribonuclease. Removal of the poly(A) tail also makes mRNAs susceptible to degradation by cytoplasmic exosomes containing 3′→5′ exonucleases.

TLS Online TPP Program

#Id: 6763

#Unit 3. Fundamental Processes

The 5′→3′ exonuclease pathway predominates in yeast, and the 3′→5′ exosome pathway predominates in mammalian cells.  The decapping enzymes and 5′→3′ exonuclease are concentrated in P bodies

TLS Online TPP Program

#Id: 6764

#Unit 3. Fundamental Processes

The rate of mRNA deadenylation varies inversely with the frequency of translation initiation for an mRNA:  the higher the frequency of initiation, the slower the rate of deadenylation.

TLS Online TPP Program

#Id: 6765

#Unit 3. Fundamental Processes

P bodies are dense cytoplasmic domains many times the size of a ribosome. They are sites of translational repression that contain no ribosomes or translation factors. They are also major sites of mRNA degradation in the cytoplasm. Exon-junction complexes upf complex functions in nonsense-mediated decay and induces degradation of the mRNA by P body–associated 5′→3′ exoribonuclease XRN1 

TLS Online TPP Program

#Id: 6766

#Unit 3. Fundamental Processes

TLS Online TPP Program

#Id: 6767

#Unit 3. Fundamental Processes

The most well studied type of DE is the AU-rich element (ARE) AUUUA, found in the 3’ UTR of up to 8% of mammalian mRNAs