Lecture 17: Control of Gene Expression Flashcards
Structural genes
Encoding proteins
Regulatory genes
Encode products that interact with other sequences and affect the transcription/translation of them
Regulatory elements
DNA sequences that are not transcribed but play a role in regulating other sequences
DNA binding domain
60-90 AAs, responsible for forming hydrogen bonds with and binding DNA
DNA binding motif
Within the DNA binding domain, a simple structure that fits into the major groove of DNA
Operon
Promotor + additional sequences that control transcription (operator) + structural genes
DNAse I hypersensitivity sites
More open chromatin configuration, upstream of transcription start site
-include many types of regulatory elements (promotors, enhancers, etc..)
ChIP is used to
Identify DNA-binding sites of a specific protein and the locations of modified histone proteins
ChIP process
DNA-protein complexes are created, DNA is broken up and the appropriate antibody is used to bind the protein in question. The DNA bound to that protein is sequenced
Mediator
Main function is to transmit signals from the transcription factors to the polymerase
GAL4
Transcriptional activator protein that activated transcription of galactose. It is inhibited by GAL80 In the absence of galactose
Enhancer
DNA sequence stimulating transcription a distance away from promoter
Insulator
DNA sequence that blocks or insulates the effect of enhancers (it lies b/w enhancer and promotor)
Most transcriptional activator proteins affect transcription by interacting with
The basal transcription apparatus
SF2 protein alternative splicing
SF2 protein enhances the use of the second splice site producing an mRNA that encodes the small T antigen
PKM2 splice isoform
Aberrantly upregulated in tumor cells for a metabolic switch favoring aerobic glycolysis which creates energy need for tumor growth
DICER/RISC and siRNA
DS RNA is cleaved by dicer to produce siRNAs
siRNAs pair with protein to form a RISC, and then pair with complementary sequences on mRNA - RNA is cleaved and degraded
DICER/RISC and miRNA
DS RNA cleaved by DICER to form miRNAs
miRNAs join other proteins forming RISC, and imperfectly pair with mRNA- which leads to inhibition of translation
siRNA and gene silencing
Some siRNAs bind complementary sequences and attract methylating enzymes which silence the gene
Where do miRNAs and siRNAs typically bind mRNA
On the 3’ UTR
