Lecture 13 - Regulation of Glycolysis Flashcards
(16 cards)
How does shuttling in and out of the mitochondrion work
Pyruvate enters mitochondrion
Pyruvate carboxylase catalyses the formation of oxaloacetate
Oxaloacetate CANNOT get out of the mitochondrion as no transporter
Therefore, it is converted to malate, transported into the cytosol, then converted back into oxaloacetate!
Catalysed by malate dehydrogenase (mitochondrial & cytosolic)
Transported by malate transporter
What happens to G6P after it is transported into endoplasmic reticulum
The catalytic subunit of Glucose 6-phosphatase
2. A calcium binding stabilising protein called SP necessary for catalytic activity
Because of the localisation of the catalytic subunit on the luminal side of the E.R. transporter proteins are needed to transport the substrate and products into and out of the E.R. respectively.
3. A transporter protein, called T1, for the substrate of the reaction glucose 6-phosphate
4. A transporter protein termed T2 to remove inorganic phosphate from the E.R.
5. A transporter protein called T3 to transport glucose into the cytosol.
How does shuttling in and out of ER work
T1: transports glucose-6-phosphate into the lumen of ER
SP: stabilising protein. Binds Ca2+ required by G6Pase
G6Pase: catalyses G6P glucose
T2: Transports Pi to the cytosol
T3: Transports glucose to the cytosol
How are the rates of metabolic processes varied in response to changing environmental conditions
Rapid
Long-term
What factors control flux through glycolysis
Substrate availability
Rate limiting enzymes in glycolysis
Enzyme conc
Allosteric reg of enzymes
Covalent modification of enzymes
What is uptake of glucose regulated by
GLUT family of transporter proteins
What does the GLUT 1 transporter do and where is it found
Red blood cells
Controls basal glucose uptake
What does the GLUT 2 transporter do and where is it found
Liver cells, pancreatic beta cells
Uptake glucose at a rate that is proportional to amount of glucose present
Remove excess glucose from the blood
What does the GLUT 4 transporter do and where is it found
Muscle cells, Adipocytes
Remove excess glucose from the blood.
Regulated by insulin
What are the rate limiting enzymes in glycolysis reactions
Irreversible
What does insulin do to enzymes
upregulate expression of Hexokinase, Phosphofructokinase and Pyruvate kinase
How is glycolysis regulated
Allosteric control
What does PFK do
Catalyses the first unique step in glycolysis
Why is PFK2 a bifunctional enzyme
Phosphofructokinase 2
Fructose 2,6 bisphosphatase
What is PFK primarily controlled by in skeletal muscle
ATP and AMP
How is pyruvate kinase regulated
feedforward mechanism by fructose 1,6-bisphosphate
