In mammals, secondary neurulation begins at the level of the sacral vertebrae of the tail.

TLS Online TPP Program

#Id: 2455

#Unit 3. Fundamental Processes

Binding of the repressor to the operator sequence blocks binding of RNA polymerase and so inhibits transcription.

TLS Online TPP Program

#Id: 6654

#Unit 3. Fundamental Processes

TLS Online TPP Program

#Id: 6655

#Unit 3. Fundamental Processes

The phosphorylation pattern on the CTD is dynamic during the elongation process, catalyzed and controlled by multiple protein kinases, including P-TEFb, and phosphatases.

TLS Online TPP Program

#Id: 6656

#Unit 3. Fundamental Processes

Shortly after transcription initiation, Pol II is paused 30 nucleotides downstream from the initiation site, waiting for the recruitment of the capping enzymes to add the cap to the 5’ end of nascent RNA. Without this protection, nascent RNA may be vulnerable to attack by 5’–3’ exonucleases, and such trimming may induce the Pol II complex to fall off of the DNA template.

TLS Online TPP Program

#Id: 6657

#Unit 3. Fundamental Processes

TLS Online TPP Program

#Id: 6658

#Unit 3. Fundamental Processes

In the nucleus, the cap is recognized and bound by the cap binding CBP20/80 heterodimer. This binding event stimulates splicing of the first intron and, via a direct interaction with the mRNA export machinery (TREX complex), facilitates mRNA export out of the nucleus. Once reaching the cytoplasm, a different set of proteins (eIF4F) binds the cap to initiate translation of the mRNA in the cytoplasm.