Endoplasmic Reticulum Function Flashcards
What makes up the ER?
Nuclear envelope, ribosome studded ER sheets and interconnected network of smooth tubules
What are the differenced between the rough and smooth ER?
Rough - flat, ribosome studded, localised within cell body
Smooth - curved tubules, ribosome free, extends to periphery of cell
What is the function of the rough ER?
Protein synthesis
Protein quality control
Protein transport
What is the function of the smooth ER?
Calcium homeostasis
Lipid biosynthesis
Mitochondrial organisation
What is ER movement driven by?
Sliding of ER tubules by kinesin and/or dynein
What causes ER morphological variation?
Differences in curvature of membranes
What generates and stabilizes membrane curvature?
ER shaping proteins
What generates and stabilizes membrane curvature?
ER shaping proteins
What 3 features are present in ER-shaping proteins?
Posses reticulon homology domains
Localize to outer leaflet of ER bilayer via RHD
Oligomers of proteins increase curvature of ER
In cell cultures, what is the effect of increasing Reticulon expression?
Increase tubular ER
Decrease amount of sheet ER
Which ER do axons contain?
Long SER tubules
Which ER do axons contain?
Long SER tubules
What are HSPs?
Progressive retrograde degeneration of long motor neurons with the spinal ->weakness of lower limbs
What do many HSP-causing genes encode?
Proteins which localise to the SER and regulate ER-shaping eg. Spastin, Reticulon
How does disruption to the SER cause neurodegeneration?
Calcium homeostasis
Lipid biosynthesis
Mitochondrial organisation
What neurotransmitters controls Ca2+ entry?
Ionotropic neurotransmitters
What does the ER act as regarding calcium?
Calcium sink (internal store)
Activation of what causes Ca2+ release from internal stores?
InsP3 receptors (1-2-3 trisphosphate)
RYR receptors
What biosynthesis is important for neurons?
Lipid biosynthesis
Why is lipid biosynthesis important for neurons?
Capacity must match demands in order to maintain membrane requirements of distal part of neurons and Er
Why is the primary site for phospholipid synthesis and why?
ER membrane - enzymes involved are loacalised to ER
What does the ER have extensive contact with?
Mitochondria
What are 3 features of ER/mitochondrial contacts?
Stable
Stay tethered even as they move
Regulate ER/mitochondrial functions
What are 3 features of ER/mitochondrial contacts?
Stable
Stay tethered even as they move
Regulate ER/mitochondrial functions
What does SER regulate?
Mitochondrial fission
What does mitochondrial network disruption contribute to?
HSP-associated neurodegeneration
What is mitochondrial disruption caused by?
Loss of ER shaping proteins
