Unit 3 Ch.17: Transcription Regulation in Eukaryotes

Misregulation of gene expression causes

numerous diseases and developmental defects

gene regulation in bacteria

transcription→ translation→ protein modification

gene regulation in prokaryotes

chromatin→ chromatin remodeling→ transcription→ splicing→ cap and tail added→ nuclear export to ribosome for translation→ protein modification

levels of regulation

transcriptional control

RNA processing control

mRNA transport and localization control

mRNA degradation control

translation control

protein degradation control

protein activity control

RNA pol II

protein coding genes and some noncoding RNAs

RNA pol I and III

transcribe smaller genes

rRNAs, tRNAs, and some small nuclear RNAs

chromosome territories and transcription factories

purposes not clear, occupation of discrete domains

interchromatin compartments

promoter

region of DNA recognized and bound by basic transcriptional machinery

RNA pol II and general TFs

focused promoter has how many start sites?

one start site

Dispersed promoter has how many start sites, and common in which genes?

multiple

housekeeping genes

core promoter elements

short sequences bound by specific regulatory factors, help to localize RNA poly to promoter region

Inr: initiator element

TATA box

BRE: TFII B recognition element

MRE: Motif 10 element

DPE: downstream promoter element

proximal promoter elements

located 250nt upstream of promoters

binding sites for sequence-specific DNA-binding proteins

transcription regulated by transcription factors

what are enhancers, silencers, and insulators?

transcription factors, RNA poly, and transcriptional activator proteins bind DNA and stimulate transcription

• DNA sequence stimulating transcription

• DNA sequence with an inhibitory effect

• DNA sequence that blocks or insulates the effect of enhancers

Activators vs Repressors

TFS that increase levels of transcription initiation

TFs that reduce transcription levels

functional domains

aa regions responsible for binding to DNA

motifs:

within binding domain, simple structure that interacts with the DNA

eukaryotic regulation of activation

many activators and coactivators combine to increase gene expression