Lecture 9: Protein sorting and transport I

Question 1

What is the difference between organelles?

Answer 1

-morphology
-location
-lipid composition
-protein composition

Question 2

Principles for protein transport

Answer 2

1. sorting signal
2. specific receptor
3. translocation machinery
4. protein release to new environment
5. energy input
6. protein needs to be folded/processed

Question 3

characteristics of a sorting signal

Answer 3

-be necessary (required for protein to be directed into a compartment)
-be sufficient (direct any neutral protein into this compartment)
-additional consideration (be recognized by specific receptor and remove from the protein upon arrival)

Question 4

Nucleus is surrounded by __

Answer 4

two membranes

Question 5

List four destinations for nuclear transport:

Answer 5

-nucleoplasm (matrix)
-inner nuclear membrane
-perinuclear space
-outer nuclear membrane

Question 6

Nucleoplasm is connected to cytoplasm via

Answer 6

nuclear pore

Question 7

nuclear pore

Answer 7

-site of protein transport in/out of the nucleus
-constitutively open but proteins require NLS
-NLS is not cleaved during transport

Question 8

How are proteins imported into the nucleus?

Answer 8

1. NLS
2. importin proteins bind to cargo protein NLS
3. fully folded
4. translocation machinery (nuclear pore)
5. Driving force (spatial regulation of Ran GTPases activity)

Question 9

Protein is kept unfolded by __ and requires

Answer 9

chaperone, ATP to dissociate it

Question 10

in nucleus transport is the sorting signal cleaved?

Answer 10

no

Question 11

in mitochondrial transport is the sorting signal cleaved?

Answer 11

yes