Topic 4A - Protein Transport Across Nuclear Pore Complex Flashcards
Why are the mitochondria and chloroplasts excluded from vesicular transport systems?
Because they were engulfed historically and were never a part of these transport systems
The environment inside the RER is most similar to…
The extracellular environment
Why do eukaryotes have internal membranes?
To make up for the fact that they have relatively small surface areas for molecular transport
How are organelles derived?
From the production of existing organelles
If you got rid of all the mitochondria (for example) in a cell, would the cell replace them?
No
Many sorting signals (“address”) are at the (1) of a protein
N-terminus
What is the purpose of a C-terminal sequence?
“Return address”
If a protein leaks out prematurely before it has been fully processed, it can be returned to the right place
What kind of enzyme removes signal sequences of mature peptides?
Signal peptidases
Describe the signal sequence of a protein synthesized in the cytosol which acts in the cytosol
It may not have a signal sequence
What activates a monomeric GTPase?
Binding to GTP
What inactivates a monomeric GTPase?
Hydrolysis of GTP to GDP
What is the name of the monomeric GTPase involved in transport across the nuclear pore?
RanGTP
RanGTP is only in the…
Nucleus
Ran-GDP is only in the…
Cytosol
RanGEF is only in the…
Nucleus
