Regulation of Transcription in Eukaryotes

Eukaryotic Gene Regulation

• Necessary to produce different cell types in an organism – cell differentiation

• All of the organism’s cells contain the same genome but express different proteomes due to gene regulation

  • Different proteins
  • Different amounts of the same protein

• Majority of genes regulated to ensure that  proteins are produced at the correct time and amount

• Constitutive genes: unregulated and have essentially constant levels of expression (ie actin)

Where Gene Regulation Occurs

• Transcriptional regulation is common
• RNA processing
• Translation
• Post-translation

Roles of Transcription Factors and Mediator

• Activator and repressor proteins influence ability of RNA polymerase to initiate transcription
• Many are regulated by small effector molecules
• Genes are almost always organized individually
• Regulation is more intricate than prokaryotes

Changes in Chromatin Structure

• DNA is associated with proteins to form compact chromatin
• Chromatin packing affects gene expression
• Transcription is difficult or impossible in the closed conformation of tightly packed chromatin
• Access to the DNA is allowed in the loosely packed open conformation