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20 Cards in this Set
- Front
- Back
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3 main types of protein transport? |
1. Gated 2. Transmembrane 3. Vesicular |
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When is gated transport used |
Nucleus to cytosol (similar environments) |
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When in transmembrane transport used? |
Proteins from cytosol to mitochondria or ER |
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When is vesicular transport used? |
ER to Golgi or peroxisomes |
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4 protein types found in cytosol |
1. Cytosolic 2. Nuclear 3. Mitochondrial 4. Peroxisomal |
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5 types of proteins formed in touch ER |
1. ER membrane 2. Golgi membrane 3. Plasma membrane 4. Secretory 5. Lysosomal |
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What is a sorting signal? (3) |
Amino acid sequence that relates protein's final destination Only becomes readable when the protein is in its final configuration Most common in nuclear proteins |
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Which protein type does not need sorting signals? |
Cytosolic - already there |
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True or false - sorting signals are necessary but not sufficient for protein transport |
False - they are both necessary and sufficient |
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What is nuclear import? |
Transport through nuclear pore complex |
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What are NLSs? |
Nuclear localisation signals - present on nuclear proteins to ensure selective import process |
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What do importins bind to? |
NLSs on proteins Cytosolic fibres on nuclear pore complexes |
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What enables and maintains the directionality of importin transport? |
GTPase RAN |
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What are translocator proteins? |
Allow transport through specific membranes The target and transporter protein complex docks within the membrane of target organelles |
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What two translocators are used in mitochondrial transport? |
TOM complex (outer) TIM 23 complex (inner) |
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What drags the protein through the mitochondrial membrane? |
ATPase chaperone |
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How do proteins get through the rough ER? |
Contain signal sequence that mediates attachment to ER membrane Signal recognition particles direct the signal to specific receptors in membrane |
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What is the purpose of stop transfer signals? |
Allow integration of proteins into membranes - create transmembrane proteins |
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What do ER resident proteins contain to keep them in the ER? |
An ER retention signal of 4 amino acids at the c terminus |
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Why are both forward and retrieval pathways necessary in the ER lumen secretory pathway? |
So proteins can return from the Golgi body to the ER |
