gene regulation: eukaryotes - western oregon universitywou.edu/~guralnl/311eukarygenreg.pdf ·...

Gene Regulation: Eukaryotes• Levels of Control• Genome Differences:

Prokaryote vs Eukaryote• Gene Regulation• Gene Dosage • Gene Amplification • Heterochromatin and DNA

methylation• Transcriptional Factors• Differential processing • Translational control

Levels of Control

• Transcriptional Control

• Processing • Transport • Translational Control • Ex: Globin synthesis

Genome Differences: Prokaryote vs Eukaryote

• monocistronic (though some nematodes have polygenic mRNA)

• exons and introns• histones and packaging • no simultaneous

transcription and translation

• Gene Dosage • Gene Amplification

Heterochromatin and DNA methylation

•Xic (1 Mb in length) and Xist (lacks an ORF)•Not translated•RNA product•Coats chromosome•Counting?•Progeny cells?

X-chromosome inactivation Gene Dosage compensation

Histones

•Change in chromatin structure•Lysine residues in histones•Histone acetyl Transferases (HAT)•Histone deacetylases

+Acetate group

Promoters: Pro vs Euk

Base level of transcription

Transcriptional Control: Cis Factors

• DNA Sequences• TATA box • Enhancers

•Cis acting elements•Enhancers: upstream/downstream•Can be inserted into the gene•Tissue specific

Mutations

Enhancers

Trans Factors

• Proteins: receptor complex

• Binding domains: DNA & Protein binding areas

Helix-turn-helix

Trans FactorsMajor groove of DNA

zinc fingers and leucine zipper looping of DNA

Example: Steroids

Alternative gene splicing

Differential processing

Humans and Chimps

Translational control

• mRNA stability• ½ life and turnover• Feedback inhibition