E2: Regulation Of Lipid Storage And Mobilization, Chang

Front 1

acetyl CoA is transported from the mitochondria to cytosol in the form of ____

Back 1

citrate

Front 2

where are the enzymes for fatty acid synthesis located?

Back 2

cytosol

Front 3

two major enzymes involved in the synthesis of fatty acids

Back 3

acetyl CoA carboxylase
fatty acid synthase

Front 4

shuttle that transports acetyl CoA out of the mitochondria and into the cytoplasm for fatty acid synthesis

what happens to citrate in the cytoplasm?

Back 4

citrate shuttle

it is cleaved by ATP-citrate lyase into acetyl CoA and oxaloacetate

Front 5

1st important step in fatty acid synthesis outside of the mitochondria

major site of regulation of fatty acid synthesis

Back 5

acetyl CoA to malonyl CoA via acetyl CoA carboxylase

Front 6

what cofactors are required in the reaction involving acetyl CoA carboxylase?

Back 6

ATP, CO2, Mg++, Biotin

Front 7

two ways in which acetyl CoA carboxylase can be regulated

Back 7

allosterically or via phosphorylation

Front 8

how is acetyl CoA carboxylase regulated by phosphorylation?

Back 8

high levels of AMP activated AMP-activated protein kinase (AMPK), which phosphorylates acetyl CoA carboxylase, inhibiting its activity

insulin, glucagon, and epinephrine also have phosphorylating effects via PP1 and PKA

Front 9

how does citrate allosterically activate acetyl CoA carboxylase?

what molecule counters this effect?

Back 9

by facilitating polymerization of inactive dimers into active filaments

palmitoyl CoA

Front 10

fatty acid synthase is made up of ____ and ____

Back 10

enzymes and acyl carrier proteins

Front 11

the primary fatty acid synthesized by fatty acid synthase is ___

Back 11

palmitate

Front 12

precursor molecules needed to form palmitate

Back 12

8 acetyl CoA's, 7 of which are converted to malonyl CoA

Front 13

structure of fatty acid synthase

how many fatty acids can be synthesized simultaneously?

Back 13

dimer of identical polypeptides, head to tail

two

Front 14

three metabolic enzymes affected by acetyl CoA levels

Back 14

ketothiolase (beta oxidation, inhibited)
pyruvate carboxylase (gluconeogenesis, activated)
pyruvate dehydrogenase (glycolysis, inhibited)

Front 15

two metabolic enzymes affected by citrate levels

Back 15

acetyl CoA carboxylase (fatty acid synthesis, activated)
phosphofructokinase (glycolysis inhibited, HMP shunt increased for NADPH production)

Front 16

two processes inhibited by high levels of malonyl CoA

Back 16

fatty acid synthesis and beta oxidation

Front 17

two processes inhibited by high NADH levels

Back 17

TCA cycle and beta oxidation

Front 18

in most tissues, triglyceride synthesis starts with ___

Back 18

glycerol 3-phosphate

Front 19

major building block for the synthesis of triglycerides, in tissues other than adipose tissue

Back 19

glycerol

Front 20

enzyme that adipocytes lack, which makes them unable to use glycerol as a substrate for triglyceride synthesis

Back 20

glycerol kinase

Front 21

mechanism for triglyceride synthesis found in adipose tissue as well as the liver

Back 21

DHAP from glycolysis to glycerol 3-phosphate via glycerol phosphate dehydrogenase

Front 22

4 general steps of TG synthesis in the cytosol

Back 22

formation of glycerol 3-phosphate
activation of fatty acid to form acyl CoA
formation of phosphatidic acid
formation of TG

Front 23

the major building block of TG synthesis

Back 23

formation of glycerol 3-phosphate

Front 24

mechanism for G3P to TG

Back 24

acyl transferase transfers 2 FA's to positions 1 & 2 on G3P, forming phosphatidic acid
phosphatase removes phosphate from phosphatidic acid, forming diglyceride
acely transferase transfers FA to position 3 of diglycerol, forming TG

Front 25

the rate of TG formation in adipocytes is dependent upon ___, which is dependent upon ___

Back 25

glycerol 3-phosphate availability

glucose level

Front 26

what happens to TG that is formed in the liver

Back 26

packaged in VLDL's, which travel to adipocytes
as VLDL's pass through capillaries, TG is hydrolyzed by lipoprotein lipase, and FA's enter adipocytes

Front 27

the rate of lipolysis is controlled by the activity of what enzyme?

Back 27

hormone-sensitive lipase

Front 28

the role of hormone sensitive lipase (HSL) and perilipin A in lipolysis

Back 28

protein kinase A (from glucagon, ACTH, epi/norepi) phosphorylates HSL and perilipin A
HSL is translocated to the surface of the lipid droplet in the cell
perilipin A results in physical alteration of the droplet surface which assists in HSL's translocation