Triacylglycerol synthesis Flashcards

1
Q

Kennedy pathway

A

Starting material is Glycerol-3-phosphate. GPAT adds first fatty acid from FA CoA. AGPAT uses FA CoA to add the second FA. PAP then removes the phosphate group and DGAT adds the last FA CoA to make triacylglycerol.
4 rxns
GPAT–>AGPAT–>PAP–>DGAT

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2
Q

Where are the substrates for TG synthesis coming from

A

Derived from glucose (glycolysis)

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3
Q

T/F fatty acids used to synthesize TG have to be bound to CoA to be activated

A

true

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4
Q

Which GPAT are in the mitochondria and which are in endoplasmic reticulum

A

GPAT1 and GPAT2 are in mitochondria
GPAT3/10 and GPAT4/6 in endoplasmic reticulum

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5
Q

Which GPAT is important for TG production

A

GPAT 3 and 4 because it they are found in adipose tissue

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6
Q

What do GPAT3 and 4 do

A

Produce 1-acylglycero-3-phosphate for TG biosynthesis. GPAT4 can compensate for GPAT3

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7
Q

How many AGPATs are there and which is the most used

A

AGPAT 2

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8
Q

what is Berardinelli-Seip Syndrom

A

human without AGPAT2
Lipodystrophic disease
inability to synthesize TG
No AGPAT activity even though AGPAT2 is the only one impaired
TG accumulates in the liver resulting in liver damage
lack adipose tissue
Free fatty acids get redirected to the liver

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9
Q

How can adipose tissue be visualized

A

MRI

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10
Q

What does Phosphatidate phosphohydrolase do

A

catalyzes phosphatidate to 1,2-diacylglycerol
removes phosphate group

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11
Q

What happens to DG and TG in yeast without Pah1P

A

DG and TG levels decrease

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12
Q

What are fld mice

A

fatty liver dystrophy. Has a spontaneous mutation that results in almost no TG. Insulin resistant. Hypertriglyceridemia
mutation in the lipin gene

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13
Q

is there a human version of Pah1

A

lipin

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14
Q

what is the function of Lipin

A

transcriptional coactivator
Works with other transcription factors to activate genes needed for FA oxidation
is also an enzyme and accounts for all PAP activity in adipose tissue

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15
Q

Where is lipin1,2,3 expressed

A

Lipin1 mainly in adipose
2 and 3 in liver not in adipose

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16
Q

What does DGAT do

A

adds the third and final FA to 1,2-diacylglycerol

17
Q

What is ACAT 1 and 2

A

catalyzed cholesterol and FA-CoA to cholesterol ester

18
Q

how was DGAT discovered

A

Initially called ACAT3 because it shared similarities with ACAT 1 and 2. It didnt have the same activity as the two others. After trying to find the substrate for the enzyme it was found it acts on diacylglycerol. it was found it adds the final FA to diacylglycerol and was renamed to DGAT

19
Q

What happened to DGAT1 knockout mice

A

Still had TG and adipose but had decreased fat mass and TG. DGAT2 compensates, no fatty liver.
Found that they were resistant to diet-induced obesity when fed fatty diet
Same weight and TG when fed low fat

20
Q

How do DGAT1 ko mice synthesize TG

A

there is another DGAT enzyme that is inhibited by MG2+
called DGAT2

21
Q

What is DGAT2 inhibited by

A

Mg2+

22
Q

What happened to DGAT2 KO mice

A

Dies hours after birth because DGAT2 is essential for life. Skin abnormalities.
DGAT2 is involved in lipid metabolism in the skin

23
Q

Why do DGAT2 ko mice die

A

DGAT2 is involved in lipid metabolism in the skin and helps prevent water loss. Leads to rapid dehydration and death due to defective skin permeability barrier.

24
Q

What happens in DGAT1 and 2 KO mouse only in adipose tissue

A

Mouse is viable, still has TG in adipose tissue meaning there’s another enzyme TMEM68

25
Q

What is the PAP in yeast

A

PAH1
from the Pah1P gene

26
Q

What is the disease called which lacks AGPAT2

A

Berardinelli-Seip syndrome