PFK-2/FBPase-2 "flux controller enzyme"

Question 1

[F26P]

Answer 1

These f26p concentrations are controlled by PFK-2 and FBPase-2 which are on different domains
WHY?
In order to set you up for efficiency.
There is a homodimeric subunit, with a regulatory domain, kinase domain and phosphatase domain.

Question 2

Flux controller activity

Answer 2

controls the amount of stuff thats going through glycolysis and GNG… (which direction the stream is running in greater amounts)
The activity of PFK-2 and FBPase-2 is subject to allosteric regulation as well as covalent modification at serine, which means PKA and PP2A is involved.

Question 3

Allosteric regulation of flux controller activities

Answer 3

PFK2:
- PFK2 inhibited by citrate (as well as PFK1 to signal that TCA is not doing anything and to go do something different)
- PFK2 is activated by AMP, which means energy is low.
- also activated by F6P, which is the substrate of PFK-2

FBPase:
-FBPase-2 is inhibited by F6P because its a product of FBPase-1, and is indicating you want to run glycolysis.
- FBPase2 activated by G3P because telling you you have energy available to run GNG, and ATP/NADH is coming from B-ox, using G3P as a surrogate to tell you that. (not using FA in GNG, but need to breakdown to product ATP/NADH, so telling you that its coming to run GNG)