lecture 13: choline

Question 1

CHTs

Answer 1

choline transporter
high affinity, saturable, sodium dependent, provide choline for acetylcholine synthesis in the presynaptic nerve terminal

Question 2

main form of choline in food and body

Answer 2

PtdCho, phospholipid with choline as polar head group, member of lecithin (amphipathic)

made by CDP-choline pathway or PEMT pathway

Question 3

low affinity sodium independent choline transporters

Answer 3

provide choline for phospholipid synthesis

Question 4

metabolism of choline

Answer 4

liver
1) phospholipid biosynthesis
2) conversion to methyl donor betaine

neurons: converted to acetylcholine

Question 5

PtdCho in liver

Answer 5

membrane biogenesis
formation of bile
secretion in VLDL (VLDL transports it)

Question 6

PEMT pathway

Answer 6

makes choline from another precursor molecule

PE (non-choline substrate) > PtdCho via PEMT via 3 steps

methyl donor = AdoMet

Question 6

CDP-choline pathway

Answer 6

produces most of the PdtCho
impairment leads to apoptosis
begins with choline

1) phosphorylated by choline kinase
2) phosphocholine activated to CDP choline (rate limiting, catalyzed by CT)
3) transfer of phosphocholine to TAG via CPT > PtdCho

Question 7

CT enzymes

Answer 7

phosphocholine to CDP choline

translocates to nuclear membrane in response to PtdCho degradation, FAs, DAGs, regulates binding, increased PtdCho synthesis

inactive soluble form and active membrane-bound form

Question 8

packing stress

Answer 8

activating lipids or PtdCho depletion increases membrane lateral stress

affects CT binding?

Question 12

Acetylcholine

Answer 12

neurotransmitter, controls output of many organs

Question 13

choline acetyltransferase

Answer 13

choline + acetyl-CoA > acetylcholine

Question 13

in neuron, choline not used for PtdCho is…

Answer 13

choline acetylated by ChAT to generate acetylcholine

acetylcholine packaged into synaptic vesicles

[ADD]

Question 14

where does free choline for acetylcholine synthesis come from?

Answer 14

low affinity transporter > PtdCho hydrolyzed to phospholipase D > free choline for acetylcholine biosynthesis

Question 15

choline deficiency

Answer 15

fatty liver and liver dysfunction are main clinical manifestations

Question 16

why is it that fatty liver and liver dysfunction would be the main symptoms of choline deficiency?

Answer 16

VLDL PRODUCTION
transporter of lipids is not being excreted, it needs the PtdCho
can’t transport lipids in the liver without VLDL
inability to remove fat being produced in the liver