Human Gene Transcription Flashcards
What is an example of a nonspecific protein?
pre-initiation complex
What are examples of a nonspecific element?
- TATA sequence
- nonspecific DNA sequences
How is transcription activated at the right time at the right place?
Specific proteins and elements
What subunit of TF2D binds to the TATA box?
TBP
Why is the H3K4 methylation needed?
- the TATA box is only 4 NT
- SSDBP (Sequence specific DNA Binding Proteins) recognize ~10 NT
What are the characteristics of nonspecific proteins?
- termed GTFs
- have RNA polymerase
- Facilitate positioning RNA Polymerase II to the proper start site for transcription .
- Assemble at the TATA box.
- Function in all RNA Polymerase II promoters.
- Are represented by TFIIX, where X can be any of A-H, each a different protein
Where does TF2H phosphorylate RNA polymerase 2?
on serine 5 of the carboxy terminal domain -> starts transcription
What is the carboxy temrinal domain a repeat of?
Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7
What starts the PIC?
TBP & TAF (TF2D)
What recognizes the TATA box?
TF2D
What unwinds DNA at transcription start point & phosphorylates Ser5?
TF2H
TF2D is composed of what 2 subunits?
TBP & TAFs
What subunit of TF2D binds directly to DNA & which does not?
- TBP -> binds
- TAF -> DOES NOT
What is the role of TAFs?
bind seuqence specific transactivators
What is developmental eukaryotic transcription?
transcription of different genes in different tissues or at different developmental stages
What is inducible eukaryotic transcription?
transcription of genes in response to a hormone
What are the 2 examples of developmental eukaryotic transcription?
- global switching = biochemical change from fetal to adult hemoglobin
- heart morphology = morphological change
How do transavtivators recruit TF2D to the TATA box?
by binding to the TAFs
What is the function of the transactivation domain?
- contacts other proteins, mainly TAFs
- helps TF2D stabilize the PIC
What is the function of the binding domain?
binds a specific DNA sequence
What is a consensus sequence?
general sequence that works for many different genes
The more transactivators in DNA looping to stabilize PIC = …
more likely for successful transcription
Do co-activators or repressors have a DNA binding domain?
no
How do co-acticators interact with DNA binding proteins?
- Most recruit HATs or contact the PIC
- Same role as transactivators; however, coactivators don’t bind a DNA sequence but rather bind to a DNA protein that binds to the DNA sequence
- Interact with DNA binding proteins
What are the characteristics of co-repressors?
- interact with DNA binding proteins
- recruit HDACs
- DO NOT bind DNA
What is an example of a classical repressor?
Rb protein
What 2 things interact with DNA but do not bind to DNA itself?
co-activators & co-repressors
What is the humanonco protein?
MYC
What are the 7 types of biochemical mechanisms that activate transactivators?
- protein synthesis
- ligand binding
- covalent modification
- addition of 2nd subunit
- unmasking
- stimulation of nuclear energy
- release from membrane
From the pituitary hormone deficiency article, what is it caused by?
heterozygosity for two novel mutations in the POU domain of the POU1F1 gene
From the pituitary hormone deficiency article, what is required for the transcription of the GH-, PRL-, and TSH-genes in the anterior pituitary?
transcriptional activator POU1F1
From the pituitary hormone deficiency article, several mutations in the gene encoding POU1F1 resulted in what?
combined pituitary hormone deficiency involving GH-, PRL-, and TSH
From the pituitary hormone deficiency article, patients with that phenotype can have what type of mutations?
either a dominant negative mutation in codon 271 (R271W) or are homozygous for a recessive mutation in the POU1F1 gene
From the pituitary hormone deficiency article, what did the boy described have?
- 1-bp deletion frameshift mutation (747delA) which leads to a nonfunctional truncated protein lacking the entire DNA binding domain of POU1F1
- a missense mutation in the C-terminal end of POU1F1(W193R)
From the pituitary hormone deficiency article, is the POU domain a type of DNA binding domain or type of transactivation domain?
POU1F1 is a transcription activator for GH, PRL, and TSHs in the anterior pituitary, the mutation describes causing a complete lack of DNA binding domain in POU1F1 meaning that the POU domain is a type of DNA binding domain
From the pituitary hormone deficiency article, “dominant negative mutation”, mentioned above in the case, means that the protein with this mutation would prevent transcriptional activation even if the protein encoded by the other allele was a wild-type protein. Describe a molecular mechanism that would account for this effect.
- Being a dominant negative mutation allows for the alleles to be heterozygous for the trait, but for the trait to still be expressed.
- Wild-type means a normal allele aka a functioning POU domain
From the pituitary hormone deficiency article, would you expect the promoter regions for GH, PRL and TSH to be identical, different, similar?
expect the promoter regions to be similar
In the melanoma reading, the oncogenes affect what?
the RAF/MEK/ERK (MAPK) pathway