3.2 - Nucleus Flashcards
evidence for nuclear membrane and endomembrane system evolving from plasma memb
is two layered membrane
what does inner nuclear membrane contain
proteins that bind to chromosomes and lamina
what is nuclear lamina made up of
lamins - a type of intermediate filaments
what type of moelcules can diffuse freely through pores?
small water soluble molecuels
NLS meaning
nuclear localisation signal
targets proteins TO nucleus
common feature of NLS
high proportion of positively charged (basic) amino acids
Arg/Lys
often short, located anywhere in protein
are NLS removed after protein has been targetted and why?
no, some proteins shuttle in and out of nucleus so needs to stay
what directs the receptor NLS compound to the pore?
fibrils
can folded proteins be imported into the nucleus?
yes, nuc pores a large enough
where is Ran-GDP found
cytosol
what maintains Ran-GDP
Ran-GAP (a regulatory protein)
triggers GTP hydrolysis, so turns Ran GTP (that’s coming out of the nucleus) into Ran GDP
where is Ran-GTP found
nucleus
what maintains Ran GTP
Ran GEF (a regulatory protein)
promotes exchange of GDP for GTP, so changes the RanGDP that’s coming in from the cytosol
effect of Ran GTP binding to receptor
displaces cargo protein from receptor
what can raised Ca levels do in terms of regulating import and export of proteins
causes conformational change in NFAT (which is a type of transcription factor) which exposes the NLS
allowing it to be imported into nucleus
