Regulations of Glycolysis Flashcards
What are the two ways to regulate glycolysis?
1) control glucose intake
2) control regulatory enzymes.
Cells regulate glucose intake using transporters? List function of each GLUT 1-5
1, 3(brain): regulated by [glucose]
2: Bidirectional
4: Moved to surface when insulin is high.
5: Fructose (liver/sperm)
How is glucose kept inside cells?
by phosphorylating glucose to glucose-6-phosphate
Hexokinase is in ___ tissues. Has a ___km value for glucose, and is inhibited by _____. This is done to prevent all ___ uptake
Why is this good for brain?
most
low
glucose-6-phosphate
( P )
Need to run glycolysis even when glucose [c] is low
___ is a hexokinase isoform, utilized by ____ cells. Has a ___ km value for glucose, and is inhibited by ___. This tells the cell that _____ is ____, and allows glucose to be utilized for ___. ALSO insulin increases ____ of ___;
glucokinase,
liver/pancreas, higher, fructose-6-phosphate, glycolysis, saturated, glycogen synthesis, transcription, glucokinase gene.
Explain the process by which glucokinase is inhibited/reactivated.
I: F6P promotes glucokinase binding to GKRP, in the nucleus.
**overcome by high glucose.
RA: F1P (fructose) promotes glucokinase unbinding from GKRP
Name the Allosteric inhibitors –> stop glycolysis
ATP (already high energy)
Citrate (FA available)
H+ (no more acidic lactate production)
Name the Allosteric Activators –> enhance glycolysis
AMP (low energy)
fructose 2,6-bisphosphate
(by hormonal regulation)
_____ is a regulatory enzyme that produces ____ which i an ____ of _____
PFK-2 (6-phophofructo-1-kinase); fructose 2,6-bisphosphate; allosteric activator; PFK-1/glycolysis
Glucagon/Insulin is released during ___ conditions. Glucagon/Insulin activates ____ , which ____ both parts of PFK-2. PFK-2(K)/(P) is _____ when phosphorylated. Glucagon/Insulin ____ glycolysis.
(starving/fed) (pKA/phosphatases) (phosphorylate/remove (P)) (inactive/active) (inhibits/promotes)
EXPLAIN!
In the heart muscle, PFK1 and hormone epinephrine has an opposite effect explain?
when the phosphatase subunit is phosphorylated it doesn’t work and the kinase does. Epinephrine phosphorylates the kinase leading to F2,6 BS–> increased PFK1 act –> transcription
Name the allosteric/hormonal inhibitors of PK
ATP (high intracellular energy)
Alanine (starting material for gluconeogenesis, liver specific); glucagon: by activation of Protein Kinase A via adenylate cyclase mediated incr [cAMP]
F16BP, INSULIN
Name the allosteric/hormonal activators of PK
Fruc-1,6BisP; Feed Forward Activ.
⁃ Incr’d PFK1 activity (production of Fruc-1,6BisP) activates PK
Insulin: Inhibition of Protein
Kinase A via phosphodiesterase mediates decr [cAMP]
Normal levels of ATP are observed in reticulocytes of patients with pyruvate kinase deficiency (residual PK activity) but not in mature red blood cells. ID the relationship of this deficiency to hemolytic
anemia
ATP production inhibited by lack of fxn’ing Pyruvate Kinase
Build up of proximal intermediates w/ decreasing lactate and pyruvate levels
Reticulocytes (young RBC) contain mitochondria and can produce ATP w/other molecules
Other wise lack of ATP inhibits fxn of Na/K ATPase which causes cell lysis - Hemolytic Anemia
Normally when PFK2’s Kinase Portion is (P), it is _______ and ______ when its Kinase portion is ________ it is active;
However in the heart epinephrine stimulates glycolysis so the PFK2’s Kinase Portion is ____ when it is (P), and inactive when it is not.
inactive
active
not phosphorylated
active _ E (P)
