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J Mol Biol. 2002 Jun 7;319(3):703-14.

Mediator factor Med8p interacts with the hexokinase 2: implication in the glucose signalling pathway of Saccharomyces cerevisiae.

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Departamento de Bioquímica y Biología Molecular, Inst. Univ. de Biotoecn. de Asturias, Universidad de Oviedo, 33006 Oviedo, Spain


In the presence of glucose the protein hexokinase 2 (Hxk2p), normally resident in the cytosol, is translocated to the nucleus where it impairs the activation of transcription of the glucose-repressed genes HXK1, GLK1 and SUC2, and promotes the activation of transcription of the glucose-induced genes HXK2 and HXT1. Here, we demonstrate the involvement of an heptameric motif, named the MED8 site, in the direct binding of the mediator protein Med8p, either as a monomer or as a homodimer. Because this site was previously involved in the Hxk2p-dependent glucose-induced regulation of gene transcription, we tested whether Hxk2p interacts with Med8p. Our results show that Hxk2 and Med8 proteins are physically associated and that this Hxk2p-Med8p interaction is of physiological significance because both proteins have been found interacting together in a cluster with DNA fragments containing the MED8 site. We conclude that Hxk2p operates through the MED8 site, by interacting with Med8p, in the glucose signal transduction pathway of Saccharomyces cerevisiae.

[Indexed for MEDLINE]

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