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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1997-7-3
pubmed:abstractText
In Saccharomyces cerevisiae, there are a large number of genes (HXT1-HXT17/SNF3/RGT2) encoding putative hexose transporters which, together with a galactose permease gene (GAL2), belong to a superfamily of monosaccharide facilitator genes. We have performed a systematic analysis of the HXT1-7 and GAL2 genes and their function in hexose transport. Glucose uptake was below the detection level in the hxt1-7 null strain growing on maltose. Determination of the kinetic parameters of individual hexose transporter-related proteins (Hxtp) expressed in the hxt null background revealed Hxt1p and Hxt3p as low-affinity transporters (Km(glucose) = 50-100 mM), Hxt2p and Hxt4p as moderately low in affinity (Km(glucose) about 10 mM), and Hxt6p, Hxt7p as well as Gal2p as high-affinity transporters (Km(glucosse) = 1-2 mM). However, Hxt2p kinetics in cells grown on low glucose concentrations showed a high-affinity (Km = 1.5 mM) and a low-affinity component (Km = 60 mM). Furthermore, we investigated the involvement of glucose transport in glucose signalling. Glucose repression of MAL2, SUC2 and GAL1 was not dependent on a specific transporter but, instead, the strength of the repression signal was dependent on the level of expression, the properties of the individual transporters and the kind of sugar transported. The strength of the glucose repression signal correlated with the glucose consumption rates in the different strains, indicating that glucose transport limits the provision of a triggering signal rather then being directly involved in the triggering mechanism.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0014-2956
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
245
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
324-33
pubmed:dateRevised
2007-7-23
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Kinetic characterization of individual hexose transporters of Saccharomyces cerevisiae and their relation to the triggering mechanisms of glucose repression.
pubmed:affiliation
Institut für Mikrobiologie, Heinrich-Heine-Universität, Düsseldorf, Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't