Lecture 9 Flashcards
(24 cards)
What are cis-regulatory elements?
DNA sequences forming part of a gene and involved in its regulation
What are response elements?
Cis-regulatory elements that specify how gene expression responds to particular signals
What are metallothioneins?
Small proteins that bind metal ions
What are two functions of metallothioneins?
Bind toxic metal ions -protect organisms from their effects
Store needed metal ions -zinc
In humans, transcription of the metallothionein gene is induced by what?
Metal ions -e.g the ore zinc in the cell the more metallothionein is needed
Glucocorticoid hormone
What are the cis regulatory elements involved in the human metallothionein gene transcriptions and its regulation?
TATA box -promoter
Increase basal-level expression
GC box (GGGCGG)
BLE
TRE (thyroid response elements)
Response elements:
MRE (metal response elements)
GRE (glucocorticoid response elements)
What does each cis-regulatory element bind?
Specific transcription factors
What TF binds to BLE?
AP2
What TF binds to TRE?
AP1
What TF binds to the GC box?
SP1
What binds to the MRE?
MTF1 -when activated by binding zinc ion
What binds to GRE?
Glucocorticoid receptor protein -when activated by binding glucocorticoid hormone
What is the core promoter?
defines where RNA polymerase binds
What is the proximal promoter?
Region near core promoter containing cis-regulatory elements
What are enhancers?
Cis-regulatory elements far from the core promoter.
Position is not critical.
How are cis-regulatory elements recognised?
By their similarity to consensus sequences -10bp
What are consensus sequences recognition sites for?
Particular activator or repressor proteins that bind specifically to this sequence (these are transcription factors)
What is the most important glucocorticoid hormone?
Cortisol
When is cortisol released?
During starvation or intense exercise; low blood glucose
What does cortisol do?
Binds to glucocorticoid receptor.
Its physiological effects:
Increase blood sugar
Anti-inflammatory -inhibition of transcription
Responses to glucocorticoid receptor depend on…
cell type. e.g liver cells
How does the receptor respond in liver cells?
Glucocorticoids increase glucose production via gluconeogenesis from amino acids and small molecules
Receptors for steroid hormones, thyroid hormones and retinoic hormones constitute a superfamily of?
Ligand responsive transcription factors (ligand means binding)
All ligand responsive transcription factors have similar structures. They are made up of domains with distinct functions. They:
Bind to DNA
Interact with the transcription complex to regulate transcription
