Clustered dispersions

Social groups

Clustered resources

Offspring that remain close to their parents.

TLS Online TPP Program

#Id: 6496

#Unit 3. Fundamental Processes

TFIIH is the only general transcription factor that has multiple independent enzymatic activities. Its several activities include an ATPase, helicases of both polarities, and a kinase activity that can phosphorylate the CTD tail of RNA polymerase II (on serine 5 of the heptapeptide repeat). TFIIH is an exceptional factor that may also play a role in elongation.

TLS Online TPP Program

#Id: 6497

#Unit 3. Fundamental Processes

On a linear template, ATP hydrolysis, TFIIE, and the helicase activity of TFIIH (provided by the XPB and XPD subunits) are required for polymerase movement. This requirement is bypassed with a supercoiled template. This suggests that TFIIE and TFIIH are required to melt DNA to allow polymerase movement to begin. To extend elongation into the transcription unit, a kinase complex called P-TEFb is required. P-TEFb contains the CDK9

kinase, which is a member of the kinase family that controls the cell cycle. P-TEFb acts on the CTD to phosphorylate it further on serine 2 of the heptapeptide repeat.

TLS Online TPP Program

#Id: 6498

#Unit 3. Fundamental Processes

TLS Online TPP Program

#Id: 6499

#Unit 3. Fundamental Processes

RNA polymerase II terminates after a short distance; small oligonucleotides of 4–5 nt are unstable; crystal structures of these RNA/DNA hybrids are unordered. Only longer hybrids have proper base pairing. The short RNA products are degraded rapidly. The suggestion is that this abortive initiation is a form of promoter proofreading.

TLS Online TPP Program

#Id: 6500

#Unit 3. Fundamental Processes

To extend elongation into the transcription unit, a kinase complex called P-TEFb is required. P-TEFb contains the CDK9 kinase, which is a member of the kinase family that controls the cell cycle. P-TEFb acts on the CTD to phosphorylate it further on serine 2 of the heptapeptide repeat.

TLS Online TPP Program

#Id: 6501

#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. Most oft the basal transcription factors are released from the promoter at this stage.