Endoplasmic Reticulum Function

Question 1

What makes up the ER?

Answer 1

Nuclear envelope, ribosome studded ER sheets and interconnected network of smooth tubules

Question 2

What are the differenced between the rough and smooth ER?

Answer 2

Rough - flat, ribosome studded, localised within cell body
Smooth - curved tubules, ribosome free, extends to periphery of cell

Question 3

What is the function of the rough ER?

Answer 3

Protein synthesis
Protein quality control
Protein transport

Question 4

What is the function of the smooth ER?

Answer 4

Calcium homeostasis
Lipid biosynthesis
Mitochondrial organisation

Question 5

What is ER movement driven by?

Answer 5

Sliding of ER tubules by kinesin and/or dynein

Question 6

What causes ER morphological variation?

Answer 6

Differences in curvature of membranes

Question 7

What generates and stabilizes membrane curvature?

Answer 7

ER shaping proteins

Question 8

What generates and stabilizes membrane curvature?

Answer 8

ER shaping proteins

Question 9

What 3 features are present in ER-shaping proteins?

Answer 9

Posses reticulon homology domains
Localize to outer leaflet of ER bilayer via RHD
Oligomers of proteins increase curvature of ER

Question 10

In cell cultures, what is the effect of increasing Reticulon expression?

Answer 10

Increase tubular ER
Decrease amount of sheet ER

Question 11

Which ER do axons contain?

Answer 11

Long SER tubules

Question 12

Which ER do axons contain?

Answer 12

Long SER tubules

Question 13

What are HSPs?

Answer 13

Progressive retrograde degeneration of long motor neurons with the spinal ->weakness of lower limbs

Question 14

What do many HSP-causing genes encode?

Answer 14

Proteins which localise to the SER and regulate ER-shaping eg. Spastin, Reticulon

Question 15

How does disruption to the SER cause neurodegeneration?

Answer 15

Calcium homeostasis
Lipid biosynthesis
Mitochondrial organisation

Question 16

What neurotransmitters controls Ca2+ entry?

Answer 16

Ionotropic neurotransmitters

Question 17

What does the ER act as regarding calcium?

Answer 17

Calcium sink (internal store)

Question 18

Activation of what causes Ca2+ release from internal stores?

Answer 18

InsP3 receptors (1-2-3 trisphosphate)
RYR receptors

Question 19

What biosynthesis is important for neurons?

Answer 19

Lipid biosynthesis

Question 19

Why is lipid biosynthesis important for neurons?

Answer 19

Capacity must match demands in order to maintain membrane requirements of distal part of neurons and Er

Question 20

Why is the primary site for phospholipid synthesis and why?

Answer 20

ER membrane - enzymes involved are loacalised to ER

Question 21

What does the ER have extensive contact with?

Answer 21

Mitochondria

Question 22

What are 3 features of ER/mitochondrial contacts?

Answer 22

Stable
Stay tethered even as they move
Regulate ER/mitochondrial functions

Question 23

What are 3 features of ER/mitochondrial contacts?

Answer 23

Stable
Stay tethered even as they move
Regulate ER/mitochondrial functions

Question 24

What does SER regulate?

Answer 24

Mitochondrial fission

Question 25

What does mitochondrial network disruption contribute to?

Answer 25

HSP-associated neurodegeneration

Question 26

What is mitochondrial disruption caused by?

Answer 26

Loss of ER shaping proteins