SUMMARY PARAGRAPH for PYK2
PYK2 is one of two S. cerevisiae genes encoding pyruvate kinase which catalyzes the conversion of phosphoenolpyruvate to pyruvate (1). Deletion of PYK2 causes no obvious growth phenotype, but a pyk2 mae1 double deletion mutant cannot grow using ethanol as the sole carbon source; MAE1 encodes malic enzyme which catalyzes the oxidative decarboxylation of malate to pyruvate (4).
Deletion of both PYK2 and CDC19, the other pyruvate kinase gene in yeast, causes a more severe growth defect than a cdc19 single deletion (1). Overexpression of PYK2 restores growth on glucose to cdc19 mutant cells (1). However, CDC19 is tightly regulated and activated by fructose-1,6-bisphosphate (FBP) whereas PYK2 is subject to glucose repression and appears to be insensitive to FBP levels, suggesting that it may be active when FBP levels are too low to activate CDC19 (1). Therefore, PYK1 appears to be the main pyruvate kinase in the glycolytic pathway (1, 5, 6).
Last updated: 2005-07-28