In normal rat kidney cells (NRK cells) a second oncoprotein (ras) is necessary for transformation.
Explanation:
The non-transformed normal rat kidney cells proliferate.
Total pyruvate kinase activity is low and M2-PK is mainly in the less active dimeric form.
Ras expression leads to an inhibition of cell proliferation.
Total pyruvate kinase activity increases and M2-PK is shifted to the highly active tetrameric form.
When both ras and E7 are expressed the cells are transformed.
Total pyruvate kinase activity is not changed but M2-PK is shifted to the less active dimeric form.
The tetrameric form of M2-PK is correlated with a high (ATP+GTP) : (UTP+CTP) ratio which means that ATP and GTP levels are high and UTP and CTP levels are low.
The dimeric form is correlated with a low (ATP+GTP) : UTP+CTP) ratio, which means that UTP and CTP levels are high and ATP and GTP levels are low.