Questions? Comments? Please contact Dr. Phillip McClean or Christina Johnson.

OVERVIEW
Flythrough Tour
~~~~~~~~~~~~
MOLECULAR PROCESSES
Transcription
Regulated Transcription
mRNA Processing
mRNA Splicing
Translation
Lac Operon
~~~~~~~~~~~~
CELLULAR PROCESSES
Protein Trafficking
Protein Modification
Protein Recycling
Insulin Signaling
Constitutive Secretion
Regulated Secretion
Mitochondrial Protein Transport
Mitosis
Meiosis
~~~~~~~~~~~~
CELLULAR ENERGY CONVERSION
Atp Synthase (Gradients)
Electron Transport Chain
Photosynthesis (Light Reaction)
Photosystem II
Glycolysis (Overview)
Glycolysis (Reactions)
Citric Acid Cycle (Overview)
Citric Acid Cycle (Reactions)
Energy Consumption
~~~~~~~~~~~~


NATIONAL SCIENCE FOUNDATION


U.S. DEPARTMENT OF EDUCATION

~~~~~~~~~~~~~
NDSU Virtual Cell YouTube
MCBE Home
Virtual Cell
WWWIC Home
Funding & Credits
~~~~~~~~~~~~~
HOME > mRNA PROCESSING > ADVANCED LOOK > 1.) CAPPING > 2.) CLEAVAGE
mRNA Processing: Advanced Look --> 2.) Cleavage

The second major step in processing pre-mRNA is the removal of a portion of its 3' end. Clicking on each of the thumbnail images will bring up a larger, labeled version of the described scene.

To see the Flash movie for the following sequence of images, click here.

Certain signal sites control where the proteins required for cleavage and polyadenylation will attach. The upstream poly(A) signal is a specific sequence of nucleotides.

The downstream poly(A) signal is not a specific sequence, rather it is a GU-rich region on the pre-mRNA.

After transcription has been completed, the first two cleavage factors attach to the up and downstream poly(A) signal sites.

These cleavage factors interact with each other to bring the signal sites into proximity with each other, forming a loop in the pre-mRNA.

Two additional cleavage factors then attach and help to stabilize the complex.

Poly(A) polymerase (PAP) then interacts with the complex and cleaves the strand of pre-mRNA at the poly(A) site.

Once cleavage has occured, most of the cleavage factors are released.

NEXT --> 3.) POLYADENYLATION

Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.