Nuclear Import and Export Flashcards
what are the 3 main structural subunits in the nuclear pore complex?
what amino acids to nuclear localisation signals contain a lot of?
how do nuclear localisation signals differ from classic membrane transport?
what is the function of importins?
they recognise proteins with nuclear localisation signals in the cytoplasm and carry them into the nucleus. they bind to the cytoplasmic filaments and are translocated through the pore by sequential binding to proteins inside the pore.
what is the function of RAN?
it binds to importin when it reaches the inside of the nucleus, changing its conformation and causing it to release its cargo protein. the importin-RAN complex is then exported through the pore. it also promotes stable complex formation between exportins and their target proteins
what is the function of RAN-Gap?
binds to the RAN-importin complex when it reaches the cytoplasm and stimulates RAN to hydrolyse its GTP to GDP, causing it to release importin into the cytoplasm. also binds to the Ran-exportin complex causing GTP hydrolysis and release of exportin and its cargo protein
what is the function of NTF2?
binds to GDP bound RAN in the cytoplasm and transports it back to the nucleus
what is the function of Ran-GEF?
binds to Ran-GDP in the nucleus, stimulating it to release GDP and bind GTP
what is the function of exportins?
recognise proteins with nuclear export sequences in the nucleus, and transports them to the cytoplasm then are recycled back into the nucleus for reuse
how can proteins be imported into the nucleus if they don’t have an import signal?
binding to nuclear import adapter proteins
what are karyopherins?
nuclear transport receptors eg importins, exportins and transportins?
what are examples of molecules transported by karyopherins?
nuclear proteins, messenger RNPs, tRNA, ribosomes
which of Ran-GTP and Ran-GDP are higher in concentration inside and outside the nucleus?
Ran-GTP is higher outside and Ran-GTP is higher inside
