Chapter 17: Eukaryotic Gene Regulation

combinatorial control

control of transcription controlled by many factors

3 kinds of combinatorial control

1. Regulatory transcription factors

   1. Small effect molecules may modulate regulatory transcription factor activity

2. Chromatin state around promoters (nucleosome arrangement and histone modifications)

3. DNA methylation

transcription factors

 regulate the ability of RNA polymerase to transcribe a given gene

general transcription factors

required for the binding of the RNA polymerase to the core promoter and its progression to the elongation state

regulatory transcription factors

bind to control elements or regulatory elements  

TFFID

general transcription factor that recruits RNA polymerase to the promoter

mediator

a protein complex that mediates between RNA polymerase II and the regulatory transcription factors 

mediator

• Mediates the interactions between RNA polymerase II and regulatory transcription factors 

  • Controls whether RNA polymerase II can progress to the elongation stage

  • Regulates the phosphorylation of RNA polymerase II CTD

3 common ways that the function of regulatory transcription factors can be affected 

1. Binding of a small effector molecule (can be inducers, corepressors or inhibitors) 

2. Protein-protein interactions 

3. Covalent modifications 

writers

enzymes that add covalent modifications to histone tails

erasers

enzymes that remove covalent modifications from histone tails 

readers

•  proteins that bind to a covalent modification to promote a downstream action 

  • Ex: maintenance of heterochromatin or recruitment of RNA polymerase