Joint 4 - Moving into Nucleus Flashcards
importance of membrane compartmentilisation?
- control protein interactions
- regulate an internal environment
- provide distinct different environment
how does a material pass by gated transport?
how does a material pass by transmembrane transport?
how does a material pass by vesicular transport?
- through pore complexes [nucleus]
- direct passage through an intact membrane
- no passage through a membrane
consequences of mis-localised proteins?
- cause disease
- caused by mutated NLS
membranes of nucleus?
- outer [continuous with ER] and inner [filaments like Lamin]
where is nuclear pore complex found and what is it?
Spans entire nucleus membrane
- 1000’s of proteins
- allows movement across it
what NUPS does the NPC contain?
transmembrane nups: anchor into mem
outer/inner core nups: anchor into mem
linker: achor FG nups
FG nups: line channel, acts as sieve
what things allow movement across nucleus?
- cargo
- NTR [aka im/exportins] - recognise proteins NLS
- GTPase Ran
structure of NTR?
heterodimer of importin a and importin b
- impA recognises NLS
- impB interacts with FG nups and bind to GTPRan {when bound it releases cargo}
process of cargo being imported in?
- NLS on cargo recognises by NTR/importin Alpha
- bind together
- b subunit interacts with FG nups and travels through
- RanGTP binds to b-importin
- cargo released
- importin left bound to RanGTP
- travels OUT and RanGTP hydrolysed to RanGDP
how can import be increased or decreased?
increased
- increase binding affinity of importin-a to cargo [phosp NLS]
- increase recognition of cargo by imp-a [phosp upstream of NLS]
- conf change to expose NLS [phos cause dimerization to expose NLS]
decrease
- cause cytoplasmic retention [NLS covered]
how does nuclear EXPORT [mrna] differ?
mrna don’t require gtp-ran gradient but other exported proteins do
