Eukaryotic Gene Regulation Flashcards
Cis-acting regulatory elements
DNA sequences close to a gene that will be regulated
Trans-acting factors
-These proteins are encoded for by different genes in the genome
-“Transit” from their site of transcription to their DNA binding sites
-Trans-acting factors bind to their specific Cis-acting element
-May have positive or negative effects
Cis Regulatory Elements
1) Basal promoter sequence
2) Proximal control regions
3) Enhancer sequence
DNA binding domwn
Transcription factors have DNA binding domains that only bind to certain DNA sequences
Dimerization Domain
Two transcription factors bind together to form a functional DNA binding unit called a dimer. Formation of a dimer adds an extra element of complexity and versatility
Activation/Repression domain
Binds to the enhancer binding proteins or other transcription factors and modulates their function
Three modes of action for transcription factors as repressors
- Competition
- Quenching
- Blocking
Quenching
Occurs when a repressor protein binds to & interferes with the DNA-binding domain of an activator protein (Repressor proteins may reduce transcription levels through quenching)
Blocking
Occurs when the repressor protein binds to the activation domain of an activator protein and prevents it from interacting with the basal transcriptional machinery
Competition
The repressor binds enhancer sequence on DNA and competes with enhancer proteins. Reduces transcription by preventing enhancer protein binding
Hypoxia Response
Reduction in normal level of tissue oxygen tension, occurs during tumorigenesis
Zinc-finger type Transcriptional Factor
Glucocorticoid receptor
miRNA-micro RNA
-Derived from specific ds-pre-miRNA species
-Regulates expression by repressing mRNA translation
-Most endogenous (from genome)
siRNA-short interfering RNA
-Derived from long dsRNAs and “random” processing
-Regulates expression by mRNA degradation
-Often exogenous (from outside the cell, virus or injected)
