Lecture 8 : Chylomicron Retention Disease

Question 1

what is chylomicron

Answer 1

particles of lipoproteins that carry fat that’s been absorbed in diet
can be taken up and used by target tissue

Question 2

where are chylomicrons synthesised

Answer 2

enterocytes

Question 3

where are chylomicrons synthesised

Answer 3

enterocytes in intestines

Question 4

where are chylomicrons assembled

Answer 4

in ER - transported to Golgi and packaged into large vesicles
released and enters capillary

Question 5

effect of chylomicron retention disease (CRD)

Answer 5

preChylomicrons accumulate in ER

Question 6

what part of ER export is defective in CRD

Answer 6

COPII coat doesnt assemble correctly on ER
leaves te preCMs trapped in ER and unable to progress

Question 7

what controls formation of COPII

Answer 7

Sar1 GTPase

Question 8

what form is Sar1 in in the cytosol

Answer 8

GDP bound
off

Question 9

how does Sar1 embed into the membrane after it activates

Answer 9

amphipathic helix flips outwards and inserts into ER membrane

Question 10

what are the 2 Sar1 isoforms

Answer 10

Sar1a
Sar1b

Question 11

what type of Sar1 pomotes export of preCM

Answer 11

Sar1b
so a mutation in this means it cant be exported

Question 12

how come Sar1b transports preCM and not Sar1a

Answer 12

Sar1b makes larger transport vesicles

Question 13

treatment of CRD

Answer 13

low-fat diet to minimise accumulation