Glycolysis: Regulation, fructose, and galactose metabolism

Fructose transporter

GLUT5

Fructokinase

Phosphorylates fructose to produce fructose 1-phosphate in the liver

Aldolase B

Splits F1P to glyceraldehyde and dihydroxyacetone (glycolytic intermediate)

Triose kinase

Phosphorylates glyceraldehyde to produces glyceraldehyde 3-phosphate (glycolytic intermediate)

What metabolism is aldolase B rate limiting for?

Fructose

Galactokinase

Phosphorylates galactose into galactose 1-P

Uridylyltransferase

Swaps Galactose 1-P and UDP-glucose to make UDP-galactose and glucose 1-P

Epimerase

Recycler in galactose metabolism. Changes configuration of UDP-galactose to make UDP-glucose

What part of galactose metabolism will enter glycolysis?

Glucose 1-P. It gets converted to G6P

Feedback inhibitor of hexokinase

Glucose 6 phosphate

What is the best indicator of the rate of ATP use: Cytosolic AMP or ATP [ ]

Cytosolic AMP

What determines AMP [ ] ?

The equilibrium position of the adenylate kinase RXN:

2ADP ←→AMP + ATP

ATP is present at much higher [ ]s than AMP or ADP. A small decrease in ATP [ ] will carry what effect?

A large increase in the AMP

During strenuous exercise, what increases the most in skeletal muscle: ATP, ADP, or AMP?

AMP. ATP decreases

What are hexokinases I-III feedback inhibited by?

Its product, G6P

Negative allosteric regulation of PFK-1

ATP

Does Fructose 2,6-bisphosphate have a negative or positive allosteric regulation on PFK-1?

Positive

If ATP negatively regulates PFK-1, will AMP also negatively regulate it?

No. It will positively regulate it

True or false: F26BP is a glycolytic intermediate

False