Liu Protein Transport

Question 0

The GTPase _____ is found in the cytosol and nucleus and is required for protein import and export from the nucleus.

Answer 0

Ran.

Question 1

T or F. Fully folded proteins can be transported in and out of the nucleus.

Answer 1

True.

Question 2

In nuclear protein transport, Ran GAP is located in the _____ and Ran GEF is located in the ______.

Answer 2

GAP in cytosol

GEF in nucleus.

Question 3

In protein nuclear import, what does GTP do? What does GTP binding do in nuclear export?

Answer 3

Nuclear import. GTP binds to nuclear import receptor, releases cargo.
Nuclear export. GTP binds to export receptor with cargo, brings it to cytosol.

Question 4

T or F. Protein translocation into the mitochondria is co translational.

Answer 4

False. protein must be fully translated.

Question 5

T or F. Fully folded proteins can be translocated into the mitochondria.

Answer 5

False. proteins are fully translated but must be unfolded.

Question 6

What are the names of the translocation receptors mitochondria have to bring in proteins from the cytosol?

Answer 6

TOM and TIM (outer and inner)

Question 7

Where on the protein is the signal sequence if a protein is destined for a peroxisome?

Answer 7

C terminal.

Question 8

Are proteins transported to peroxisomes unfolded or fully folded?

Answer 8

Fully folded.

Question 9

Assign “unfolded” or “fully folded” to the proteins translocated into the

1) nucleus
2) mitochondria
3) peroxisome

Answer 9

1) folded
2) unfolded
3) folded

Question 10

What is the name of the protein that recognizes ER signal sequences and brings the mRNA to the ER?

Answer 10

SRP Signal Recognition Protein.

Question 11

Is polyribosomal translation possible in mRNA translated on the surface of ER?

Answer 11

Yes.

Question 12

What is SEC 61?

Answer 12

ER protein translocator.

Question 13

A protein has an N terminal signal sequence, and a stop transfer sequence in the middle. Where is the N terminal, C terminal? (Cytosol, lumen of ER)

Answer 13

N terminal in lumen of ER,

C terminal in cytosol

Question 14

Imagine a protein with a signal sequence in the middle of the protein. Where is the N terminus and C terminus?

Answer 14

Tricky. It can be either orientation. N term in lumen, C in cytosol. or C in lumen, N in cytosol. Depends on which side of the SEC 61 translocator protein the signal binds to.

Question 15

Imagine a protein with a signal seqence mid protein, and a stop transport signal after (nearer C terminal). Where is the N terminus and C terminus?

Answer 15

Both N terminus and C terminus cytosolic.

Question 16

In complex multipass proteins, where is the N terminus (lumen or cytosol)?

Answer 16

lumen. a second start transfer sequence will bring the protein into the cytosol.

Question 17

What is Parkin?

Answer 17

An E3 ubiquitin ligase used in ERAD ER associated degradation.

Question 18

What are some diseases involving faulty protein degradation?

Answer 18

Cystin Fibrosis, Parkinsons

Question 19

What is Cystic Fibrosis?

Answer 19

Deletion of Phe at position 508 of Cystic Fibrosis Transmembrane conductance Receptor (CFTR). All proteins degraded by ERAD. No chloride regulation.

Question 20

What are the 3 major types of glycoproteins?

Answer 20

N linked (asparagine, GlcNac)
O linked (serine, threonine, GalNac, HyL)
GPI anchored (glycosylphosphatidylinositol links PM to protein).

Question 21

N linked glycoproteins can be further categorized to complex, hybrid and high mannose. They all share 2 ____ at the base and 2 ____ which serve as the two branches.

Answer 21

Glcnac bases, Mannose branches.

Question 22

______ inhibits the first step of N linked glycosylation (dolichol pp oligosaccharide giving oligosaccharide to Asn)

Answer 22

Tunamycin.

Question 23

How are high mannose and complex N linked glycosylation made? Start with glcnac glcnac manose manose manose glucose glucose.

Answer 23

Glucosidases and a little mannosidase used to make high mannose oligosaccharides.
Glcnac is added to prevent endopeptidases, gal is added and other random shit. makes complex oligosaccharides.

Question 24

Inside the ER lumen, the N terminus of the glycosylphosphatidylinositol attaches itself to the ____ terminus of the acceptor protein.

Answer 24

C