Flashcards in Exam III Review control of transcription initiation chapter 16 Deck (49)
Regulatory regions for genes transcribed in a cell type specific manner, always very close to the genes protein coding region. Upstream.
Part of the promoter upstream of the transcription initiation site binding of RNA polymerase occurs here, An initiation box consisting of roughly 7 nucleotide sequence T a T a (a or T) a (A or T), Allows basal level of transcription
A regulatory site that can be quite distant – up to 10,000's nucleotides away from the promoter, can augment or repress Basal levels of transcription. A single _______ may have multiple binding sites for different transcription factors. Maybe located either five prime or three prime to the transcription start site
Sequence specific DNA binding proteins that influence transcription (basal factors, activators, or repressors)
Tata box binding protein, assists in the binding of RNA polymerase II to the promoter
Basal transcription factor TBP
Tata box binding protein associated factor recruited by TBP, assists in the binding of RNA polymerase two
Basil transcription factor TAF (Tbp – associated factors)
Transcription factors that bind to enhancers to increase transcriptional activity by interacting directly or indirectly with Basal factors at the promoter. Responsible for much of the variation in levels of transcription of different genes.
The structural domain with in an activator protein which mediates binding to enhancer DNA, which interact with other proteins to activate transcription
DNA – binding domain
DNA-binding motifs found in activators
DNA binding domain helix loop helix
DNA-binding structure found mainly in eukaryotic activator proteins
DNA-binding structure found mainly in prokaryotes Activator proteins for example the lack repressor
Helix turn helix
Part of an activator that binds to DNA, binds to either identical (homodimer) or non-identical heterodimer subunits
A helix with Leucines at regular intervals, June – June homodimers May interact, June – fos heterodimers may interact. Both are motifs found in activator proteins
Leucine zipper dimerization domain
Eukaryotic transcription factors that bind specific DNA sites near a gene and prevent the initiation of transcription of the gene by recruiting call repressor proteins that either prevent the RNA polymerase II complex from finding the promoter or modify histones to close chromatin structure
Indirect repression. A protein can bind the activation domain of an activator bound to an enhancer and thereby prevent the activator from functioning
Part of the activator protein that binds to other proteins
Competition due to overlaping binding sites, quenching, (repressor blocks activation domain) cytoplasmic sequestration, heterodimerization
Ways and indirect repressor can interfere with the function of an activator
DNA sequences located between a promoter and an enhancer that block the enhancer from activating transcription from that promoter
Binds insulators and facilitates the formation of DNA loops
Ccctc binding factor CTCF
One chromatin is isolated from the cell nuclei. Two DNA and proteins are chemically cross-linked wig formaldehyde. Three DNA is fragmented by sonication. Four antibody specific to the protein of interest is used. Five DNA to which protein was bound is purified and sequenced.
Chromatin immunoprecipitation-sequencing Chip-seq)
Beyond genetics specifically beyond the nucleotide sequence of DNA (modifications)
A methyl group is added to a cytosine base that is followed by a guanine by DNA methyl transferases. Control of transcription.
Regions with a high concentration of CPG dinucleotides
When a cpg island near a promoter is unmethylated, the gene is transcriptionally active. In the absence of a transcriptional activator, the CPG Island becomes methylated. Methyl CPG binding proteins bind and close the chromatin structure.
DNA methylation at cpg islands silences gene expression
Caused by a loss of function mutations in meCPg (methyl CPG binding protein) gene on the X chromosome.
Long term repression through DNA methylation
Expression of an allele depends on the parent that transmits it. Methylation at imprinting control regions ICRs silences Jean expression.
Paternal allele is silence, maternal allele is expressed
Maternal allele is silenced, paternal allele is expressed