Which of the following is not a role of the DNAK/Hsp70 superfamily?
Stabilise nascent polypeptides
Repaor heat shocked proteins
Preserve folding proteins
Hsp70s (unlike DNAK's) do not require chaperones
What is the role of DNAJ/Hsp40 when combined with DNAK/Hsp70
Peptidyl propyl isomerases
DNAK/Hsp70 need NEF's in order to function
Where is the Hsp70/DNAK binding domain for ATP?
Name the subdomains of the ATPase found in DNAK/Hsp70
What increases the ATPase activity of the ATP binding domain?
The binding of the substrate
Movement into an acidic compartment
The core substrate binding domain has an affinity for what?
Neutral, hydrophobic aa
Acidic, polar aa
Basic, polar aa
The C-terminus of DNAK/Hsp 70 acts as a 'lid' for the protein
When ATP is hydrolysed in DNAK/Hsp70, where does the C-terminus bind to?
It doesn't move at all
Over the bound substrate
Without the assistance of DNAJ/Hsp40, the ATPase in DNAK/Hsp70 works too slowly for the C-terminus to trap the bound substrate
Hsp70/DNAK's preferred binding pattern is 15 aa long
What are the 'Flanking' residues (1-4, 9-13) of Hsp70's preferred binding site made of?
The preferred residue for the -Core- of Hsp70's preferred binding site is Valine
What other residues can make up the 'core' of the preferred binding site/
How does this 'Preferred Binding Patter' for Hsp70 help direct the protein?
In properly folded proteins, the hydrophobic stretch is hidden, and so only nascent/denatured proteins have the exposed residues for Hsp70 to bind to
In nascent/denatured proteins, these hydrophobic residues will be added by Hsp40, so it can recognise them
Stretches with the core residues are removed during protein folding, so only nascent polypeptides have them
What is the role of the J domain in a Hsp40?
Contain the HPD peptide needed to boost Hsp40's ATPase
Gly/Phe rich linker for positioning
Zn+ 'finger' for substrate binding
The role of the Gly/Phe rich linker does what?
Makes DNAJ/Hsp40 flexible enough to bind to its respective protein
Makes DNAJ/Hsp40 a more effective ATPase
Allows DNAJ/Hsp40 to locate its respective DNAK/Hsp70
The Zinc 'Finger' is for substrate binding
Which amino acids make up the HPD domain?
The Znc finger of DNAJ/Hsp40 can interact with the nascent polypeptide and bring it to the DNAK/Hsp70
What is the sequence of the Zinc 'finger'?
The C-terminus of Hsp40 is for tetramerisation
What effect does the GEF factor binding have on the Hsp70/Hsp40 complex?
ADP is replaced with ATP
ATP is replaced with ADP
Newly folded protein binds
Newly folded protein dissociates
When the substrate & Hsp40 bind to Hsp70, the GEF factor also binds
How is the nascent polypeptide transferred from the DNAJ site to the DNK site?
The G/F domain is flexible enough to bind to the DNAK site and pull it in for transfer
The J domain is pulled like a thread through the ATPase, bringing the two sites close enough together for transfer
The dimerisation of the DNAJ pulls the two sites close together
In which of the following is Prefoldin found?
Prefoldin can act as a substitute for Hsp70 if the organsim doesn't have the latter
Prefoldin is ATP dependent
Prefolding is a...
What is the role of Preofoldin in Archea?
Captures nascent polypeptides and binds them to Gro-El
Captures nascent polypeptides and binds them to CCT
Captures nascent polypeptides and binds them to SSA
In Eukaryotes, prefoldin might be specific for the folding of what?
In archea there are 6 Prefoldin genes (Grim1-6) in Eukaryotes there are 2 (Gimalpha and Gimbeta)
Which of the following describe Prefoldin
Jellyfish like structure
With 6 coiled-coil beta sheets
With 6 coiled-coil alpha helices
There are 3.5 amino acid residues per helical turn of the coiled coil helices in Prefoldin (not 3.6)
The subunits forming the dimerisation interface of the below molecule are what?
Where do the non-native proteins bind to Prefoldin?
Exposed hydrophobic residues in the distal ends of the 'tentacle'
Exposed hydrophobic residues in the proximal ends of the 'tentacle'
Exposed hydrophobic residues at the top of the 'tentacle'