Explanation:
When M2-PK (PKM2) is in the less active dimeric form all phosphometabolites above pyruvate kinase such as glycerate 3-P and fructose 1,6-P2 accumulate and are then available as precursors for synthetic processes such as nucleic acid, phospholipid and amino acid synthesis.
Consequently:
- ADP and GDP levels are high
(= substrates of PK). - ATP and GTP levels are low
(= products of the PK reaction). - Phosphometabolite levels are high.
- Product levels of synthetic processes, such as UTP and CTP are high.
- (ATP+GTP) : (UTP+CTP) ratio is low.
- Energy is provided by glutaminolysis.
- When the fructose 1,6-P2 levels reach a certain high value the dimeric form of M2-PK (PKM2) reassociates to the tetrameric form. Then glucose is converted to lactate until the fructose 1,6-P2 levels drop below a minimum signal level. As a consequence M2-PK (PKM2) dissociates to the dimeric form and this oscillating cycle starts again.