case 6

Question 1

NPC

Answer 1

-nuclear pore complex, large filled with water passage, composed of 30 diff proteins.
pores extensive sunstractured regions prevent big molecules to diffuse unselectively

-traffic both directions
-unspliced mRNA doesnt exist till its checked
-Ribosomes and RNA can be exported
-large molecule needs NLS (nuclear localization signal) (charged AAAAAA)
- bind to nuclear transport receptor
- ran-GTP bind to it and disbond the cargo in the nucleous
-returns to cytosol, gtop hydrolisis, free NTR (transport receptor, and free ran-GDP

Question 2

function of Cytosolic Fibrils

Answer 2

extind from the rim of the pore to the inside of the nucleus, helping by transport of the bonded NTR with its cargo to the inside of the nucleus.

Question 3

RAN protein

Answer 3

provides GTP for the nuclear tranport receptor inside the nucleus and discharge the cargo (protein vesicle), they move out the nucleus, GTP hydrolisis and charge the transport receptor with energy to bind to the nucer localization signal of the protein

Question 4

Some proteins have a nuclear import and export signal, why?

Answer 4

Some proteins have a nuclear import and export signal so that they can shuttle back and forth. The import and export of proteins needed in the nucleus can be regulated to control transcriptional activity.

Question 5

signaling sequence at the N-terminus goes to…

Answer 5

mitochondria

Question 6

Special about the transport inside the mitochondria

Answer 6

is the simultaneous transport of an unfolded protein across a double membrane.

Question 7

signal peptidase

Answer 7

cleave off the signaling sequence of the protein if its unnecessary for its function, in the process of translocation

Question 8

proteins that incorporate into the membrane, how to be recognised

Answer 8

throughout stop and start signales within the protein amino acid sequence

Question 9

water soluble proteins translocation

Answer 9

translocated completely into the ER for secretory pathway or for the lumen of an organelle.

Question 10

translation and translocation of protein happens at the same time

Answer 10

the signal sequence being recognised while the polychain is being synthesized

Question 11

SRP

Answer 11

signal recognition particle, direct the free or membrane-bound ribosome toward the ER translocation channels.

Question 12

why translation is slowed down when the SRP is bond to the ribosome hanged protein sequence

Answer 12

because is not recognized by the SRP receptor on the membrane of ER

Question 13

translocation channel and signaling sequence

Answer 13

signaling sequence stay attached to the translocation channel, causes a loop while the polypeptide is getting longer by translation
finally, it cleaves off, and often incorporated to the membrane of the ER

Question 14

Hydrophobic protein destiny

Answer 14

imbedded into the membrane and:
partially translocate acrose the membrane and become transmembrane proteins
translocated and become transmembraneprotein of other organelles
ALL are initially directed to the ER (by ER signal sequence of hydrophobic AA’s)

Question 15

in order to be imbeded into the ER membrane the hydrophobic start and stop sequence of the protein..

Answer 15

dispersed over the whole polypeptide sequence

Question 16

N-terminal /signaling sequence

Answer 16

initiates translocation

Question 17

Start-transfer sequence (hydrophobic)

Answer 17

is released into the bilayer but not cleaved off like the signal sequence
When only one start-transfer sequence, C-terminal faces the cytosol and N-terminal faces the lumen

Question 18

cytosol to the mitochondria, TOM complex

Answer 18

polypeptides signal sequence has special chemical properties and configurations which make them recognizable for the receptor protein in the TOM Complex.
translocate the protein across the outer membrane into the intermembrane space

it recognizes the Precursor mitochondrial protein and translocates it into the intermembrane space

Question 19

TIM 23

Answer 19

translocate the protein across the inner membrane into the matrix
binds to the protein in the intermembrane space and translocates it further into the matrix.

Question 20

protein in the matrix

Answer 20

Once introduced into the matrix the signal sequence is cleaved off and chaperones (Hsp70) help to refold the protein into its native functional shape.

Question 21

chaperones Hsp70

Answer 21

help to refold the protein into its native functional configuration

Question 22

retrieval pathway of veicular traffic

Answer 22

There is a retrieval pathway in place to possibly bring the vesicles back to its origin.