Huntington's Disease Flashcards
Is fragmentation of an unfolded protein reversible?
No
What are the three routes an unfolded protein could take?
Form an intermediate required for the final structure, aggregate disorderly or fragment.
What did Anfensen’s experiment with RNAase demonstrate?
The inherent nature of peptides to fold into the correct structure.
What is the effects of urea on proteins?
Break H bonds
What is the effect of Mercaptoethanol on proteins?
Reduce S-S bonds.
What are the three proposed mechanisms via which proteins fold?
Framework, nucleation and hydrophobic collapse.
What does the framework model of protein folding propose?
Some segments of the peptide are predisposed to form beta and some alpha structures. These form a framework for protein folding.
What does the nucleation model of protein folding propose?
One part of the protein forms a secondary structure that it is predisposed to and folding propagates outwards.
What does the hydrophobic collapse model of protein folding propose?
Hydrophobic interactions form first and the remainder forms around it.
What do the wells of an energy funnel represent?
A secondary structure that is not native and not most favourable so is reversed.
What are the two stable states a protein make take?
The native state and the amyloid fibril (beta-rich) state, which may be more stable that the native conformation.
In an amyloid, is the entire protein misfoled?
No, only part become beta-rich. The remainder is often in its native state.
What are the two major components of the kinetics of fibril formation?
Lag phase (monomer-seed) and elongation.
How are kinetics of fibril formation altered if we start with a nucleus/seed?
The lag phase is shortened.
What is one treatment option for amyloids formed from transthyretin?
Thyroid-like molecules that stabilise the tetramer state.
In how many proteins does poly-Q lead to disease?
9 proteins
How does polyQ expansion occur?
CAG regions are likely to be duplicated during replication. This causes polyQ expansion over generations.
What number of glutamine repeats be tolerated before disease occurs?
37
What disease can the Huntingtin protein lead to?
Huntington’s disease
What disease can Atrophin 1 lead to?
Dentatorubral-pallidolusysian atrophy.
What disease can the androgen receptor lead to?
Spinal bulbar muscular dystrophy
What disease can Ataxin 1, 2, 3, 6 and 7 lead to?
Spinocerebellar Ataxias 1, 2, 3, 6, 7
What disease can the TATA-binding protein lead to?
Spinocerebellar Ataxia 17
What does 9 proteins susceptible to polyQ related disease have in common?
Tendency to form beta sheets
PolyQ expansion
Tolerance of up to 37 polyQ.
Which axon of the Huntingtin gene is affected by polyQ expansion?
Axon 1
What protein is usually found in areas of Amyloid accumulation?
Ubiquitin
Can GFP-u be ubiquitinated in the presence of huntingtin aggregates?
No
Give an example of a healthy protein that amyloid aggregates can interact with?
transcriptional coactivators, e.g. CBP
What tag is used to measure beta-sheet formation and aggregation?
Thioflavin T, which binds to beta-sheets
How does polyQ expansion lead to misfolding?
Decreases stability
Does polyQ expansion increase or decrease CM?
Decrease
What is the effect of heat shock protein 70 on polyglutamine Q78 effects?
Decreases effects of polyQ78 by binding to hydrophobic domains of misfolded proteins and preventing interaction.
What is the effect of trehalose on huntingtin?
Stabilisation and treatment of Huntington’s.
