The cytokines form a family of small, secreted signaling molecules (about 160–200 amino acids) that control growth and differentiation of cells.

TLS Online TPP Program

#Id: 786

#Unit 3. Fundamental Processes

Readthrough transcripts refer to the fraction of transcripts that are not stopped by the terminator. 

TLS Online TPP Program

#Id: 787

#Unit 3. Fundamental Processes

Termination is prevented by specific ancillary factors that interact with RNA and/or RNA polymerase, a situation referred to as antitermination. 

TLS Online TPP Program

#Id: 788

#Unit 3. Fundamental Processes

Transcription initiation and termination, both require breaking of hydrogen bonds.

TLS Online TPP Program

#Id: 789

#Unit 3. Fundamental Processes

Rho factor is an essential protein in E. coli that causes transcription termination, accounts for almost half of E. coli terminators.

TLS Online TPP Program

#Id: 790

#Unit 3. Fundamental Processes

Sequences of Rho dependent transcription termination

1. Rho binds a rut site. 

2. The rho factor then tracks along the RNA until it catches up to RNA polymerase. 

3. When the RNA polymerase reaches the termination site, rho first freezes the structure of the polymerase and then invades the exit channel to destabilize the enzyme, causing it to release the RNA. 

4. Pausing by the polymerase at the site of termination allows time for rho factor to translocate to the hybrid stretch.

TLS Online TPP Program

#Id: 791

#Unit 3. Fundamental Processes

A rut site has a sequence rich in C -41% and poor in G preceding the actual site(s) of termination. The sequence corresponds to the 3’ end of the RNA.