cytoplasm Flashcards
what sorts signals for protein translocation?
linear signal sequences
what are nuclear pore complexes?
they perforate the nuclear envelope (in all eukaryotes) - has 30 different proteins (nucleoporins)
what are unstructured proteins?
proteins that lack a well-structured 3d fold, form a mesh at the inner ring
what happens to proteins with a nucleur localization sequence?
they are directed into the nucleus (adding this sends it there), they have flanking basic clustersw
what happens to proteins with a nuclear export sequence?
they leave/are sent out of the nucleus
what are the import receptors?
soluble cytosolic proteins that contain multiple low-affinity binding sites for the FG repeats found in the unstrucutred domains of several nucleoporins
what does the importin-cargo complex do?
locally disolves the mesh and can diffuse in/out of NPC pore
what is the purpose of Ran?
the Ran bound to GTP provides energy and directionality
what are importins and exportins?
importins are the receptor for NLS-containing proteins, exportins are the NES receptors
what does GAP trigger?
GTP hydrolysis Ran-GDP
what does GEF promote?
the exchange of GDP for GTP
what do the parts of importin do?
the alpha subunit bind the nuclear localization signal, and the beta subunit binds the unstructured chains
what happens to Ran in the cytoplasm?
the GTP molecule inside it is hydrolyzed and the Ran dissociates, leaving importin-beta ready to carry the next cargo protein inside
what would happen to proteins with both NESs and NLSs?
they would shuttle between the nucleus and cytosol constantly
where are most mitochondrial proteins synthesized?
in the cytoplasm
