Abstract: A complex of the transcription factors Gcr1p and Gcr2p coordinately regulates the expression of glycolytic genes in Saccharomyces cerevisiae. To understand the effects of gcr mutations on other metabolic pathways, genome-wide gene expression profiles in gcr1 and gcr2 mutants were examined. The biggest effects of gcr1 and gcr2 mutations were observed on the glycolytic genes and the expressions of most of the glycolytic genes were substantially decreased compared to those in the wild-type strain in both glucose and glycerol + lactate growth conditions. On the other hand, the expressions of genes encoding the TCA cycle and respiration were increased in gcr mutants when the cells were grown in glucose. RT-PCR analyses revealed that the expression of SIP4 and HAP5, which are known to affect the expression of some of the gluconeogenic, TCA cycle and respiratory genes, were also increased under this condition. The growth of gcr mutants on glucose was impaired by adding respiration inhibitor antimycin A, whereas the growth of the wild-type strain was not. The conversion of glucose to biomass was higher and, to the contrary, ethanol yield was lower in the gcr2 mutant compared to those in the wild-type strain. These results suggest the possibility that the gcr mutants, in which glycolytic activities are low, changed their metabolic patterns under glucose growth condition to enhance the expression of TCA cycle and respiratory genes to produce more energy. Copyright (c) 2005 John Wiley & Sons, Ltd.