Nuclear Periphery and Nucleocytoplasmic transport

Question 1

what are 3 features in the structure of nuclear envelope

Answer 1

double membrane
nuclear pore complex
nuclear envelope

Question 2

two points about nuclear pore complex

Answer 2

tight control

differs on each side of membrane

Question 3

describe a double membrane

Answer 3

two lipid bilayers

Question 4

what is the nuclear pore complex made up of

Answer 4

subunits- on average 8

Question 5

what supports the nuclear envelope

Answer 5

nuclear lamina

Question 6

why does the nuclear envelope need support

Answer 6

to strengthen
communication
etc

Question 7

where is the lamina located

Answer 7

beneath the inner nuclear membrane

Question 8

what filaments are present in lamina

Answer 8

intermediate filaments similar to cytoplasmic filaments

Question 9

how is the lamina anchored to nuclear envelope

Answer 9

membrane protein anchorage
lipid modifications of proteins on lamina to anchor
direct interactions between NPC and lamina

Question 10

what are the mutationsin lamina associated with

Answer 10

hutchinson-gilford progeria syndrome(inherited premature ageing condition)

Question 11

how do HGPS cells differ from healthy cells

Answer 11

wrinkled structure

Question 12

how do molecules get from nucleus to cytoplasm

Answer 12

nuclear pore complex

Question 13

whar are karyopherins

Answer 13

importins and exportins

move molecules in and out

Question 14

what are RanGTP/RanGDP

Answer 14

ras-related nuclear protein bound either to GTP or GDP

Question 15

what is the function of RanGTP/RanGDP

Answer 15

controls the direction of nuclear transport via a carefully maintained gradient across nuclear envelope

Question 16

what is RanGAP

Answer 16

ran GTP-ase activating protein- cytoplasmic

Question 17

what is RanGEF

Answer 17

ran guanine nucleotide exchange factor (attached to chromatin)

Question 18

what is the protein export cycle

Answer 18

moves cargo out of nucleus
must bind as trio of molecules
cargo RAM GTP can bind to export complex
goes into cytoplasm
RAMGAP enzymes spot RAMGTP in cytoplasm and remove phosphate so that RAMGTP no longer binds
complex falls apart and so RAMGDP can pass through pore on its own

Question 19

what is the protein import cycle

Answer 19

binding to importin can bind complimentary no additional factor
RAMGTP recognises importing and binds it
comformational chnage and so cargo can no longer bind
RAMGTP into cytoplasm, phosphate removed

Question 20

what is the cargo associated with facillitated diffusion model

Answer 20

importing

Question 21

how is karyopherin involved in facillitated diffusions

Answer 21

protein has binding site for FxFG repeats - FG repeats on nuclear pore proteins

Question 22

how is facciliateted diffusion helped

Answer 22

via binding with FG repeats

Question 23

where do rna exist

Answer 23

as ribonucleoprotein complexes

Question 24

describe the transport of RNAs

Answer 24

tTRNA out
hnRNA out
u-snRNA out

Question 25

what is U-snRNA

Answer 25

involved in protein assembly in cytoplasm- protein complex then imported back into nucleus

Question 26

what is a TAP complex

Answer 26

induces splice junction

Question 27

why are splice junctions important

Answer 27

when exporting

allow them to act as export proteins for RNA

Question 28

what happens to RNA as it diffuses out of pore

Answer 28

forms transient interactions with NPC and this twists RNA

RNA more likely to move in same direction

Question 29

what are Dbp5 twists

Answer 29

in RNA to make move in same direction