Transcription factors

Transcription factors are proteins that bind to DNA near the start of transcription of a gene. These proteins either inhibit or assist RNA polymerase in initiation and maintenance of transcription.

The figure shows several transcription factors (JUN, FOS, Sp1, and basal factors) that are necessary for transcription of some genes. Mutations in JUN and FOS have been found in cancer cells. Transcription factors contain several functional regions:

• Activation domain: region that interacts wtih other parts of the transcription machinery (RNA polymerase or other transcription factors).
  
  
• DNA binding domain: amino acids in the protein that recognize specific bases near the start of transcription.
  
  
• Nuclear localization domain: region that serves as a signal for the protein to go to the nucleus after being synthesized in the cytoplasm.
  
  
• Dimerization domain: Many transcription factors work as dimers (two subunits). For these proteins, a region of the protein facilitates interaction with another subunit.
  
  

	DNA Structure and Function
	DNA Replication
	Transcription
	Transcription Factors
	Signal Transduction
	Cell Cycle