Flashcards in Protein Targetting Deck (32)
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1
Where are proteins synthesised on free ribosome destined for
Cytosol, nucleus, peroxisomes and mitochondria
2
Where are protein synthesised on the RER destined for
Secretion, insertion into the membrane and lysosomes
3
What sequence do proteins destined to remain in the Er contain?
KDEL sequence
4
Where is the KDEL sequence found on proteins
C terminus
5
What proteins transport proteins with the KDEL sequence back to the ER
COP1 proteins
6
Where is the signal sequence for proteins destined to go to mitochondria found?
N terminus
7
What type of proteins bind to proteins destined to mitochondria
Heat shock proteins
8
What do heat shock proteins do?
Allow proteins to cross the mitochondrial membrane and pull the protein through the translocation machinery
9
What are the 2 translocation machine dies found the in the mitochondrial membranes
TOM (outer membrane) and TIM (inner membrane)
10
What happens to the protein once it enters the mitochondria
The protein folds and the signal sequence is cleaved
11
What is the signal sequence on proteins destined for lysosomes
Mannose-6-Phosphate
12
What do proteins destined for mitochondria contain to be recognised by enzymes that their mannose region needs phosphorylating
Signal patch
13
What happens to proteins once its bound to a M6P receptor
Transported in vesicles with a clathrate coat to lysosomes
14
What causes a dissociation between the receptor and protein
A pH change
15
What enzyme removes the phosphate group
Phophatase
16
What is I cell disease
Deficiency in the Kinase enzyme which phosphorylates the mannose group for proteins destined for lysosomes
17
What is the result of I cell disease
Bloated lysosomes as they don't have enzymes to break down their contents
18
What is the sequence for proteins destined for the nucleus called
Nuclear translocation sequence
19
What binds to proteins destined for the nucleus
Importing
20
What is the role of Ran GTP in protein targeting for the nucleus
Binds to importin causing a conformational change which displaces the cargo protein
21
What is the signal sequence for proteins targeted for peroxisomes called
Peroxisomes targeting sequence
22
Where is the peroxisomes targeting sequence found
C terminus
23
What recognises the peroxisomes targeting sequence
PEX 5 receptors
24
How do proteins destined for peroxisomes enter
PEX proteins make up a complex in th emebrsne and form a pore
25
What is Zellweger syndrome
Syndrome resulting in mutations in PEX proteins.
26
What is cotranslational transport
When proteins move from ribosomes to the Golgi then out of the cell
27
What 2 types of secretion are there
Constitutive or regulated
28
Give an example of constitutive secretion
Collagen
29
Give an example of regulated secretion
Insulin
30
