Galactose transport in Saccharomyces cerevisiae. 3. Characteristics of galactose uptake in transferaseless cells: evidence against transport-associated phosphorylation.
The characteristics of the inducible galactose transport system in bakers' yeast were studied in uridine diphosphate, galactose-1-phosphate uridylyl-transferaseless cells. Transferaseless cells transport galactose at the same initial rate as wild-type cells and accumulate a mixture of free galactose and galactose-1-phosphate. The addition of (14)C-labeled galactose to cells preloaded with unlabeled galactose and galactose-1-phosphate results in a higher rate of labeling of the free-sugar pool than of the galactose-1-phosphate pool. These results support other evidence that galactose uptake in bakers' yeast is a carrier-mediated, facilitated diffusion and that phosphorylation is an intracellular event after uptake of the free sugar.
D001692:Biological Transport; D002247:Carbon Isotopes; D002845:Chromatography; D003470:Culture Media; D004058:Diffusion; D005374:Filtration; D005690:Galactose / Q000378:metabolism*; D005827:Genetics, Microbial; D006600:Hexosephosphates / Q000378:metabolism; D008962:Models, Theoretical; D009154:Mutation; D009713:Nucleotidyltransferases / Q000378:metabolism*; D010085:Oxidative Phosphorylation; D012440:Saccharomyces / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*
D002247:Carbon Isotopes; D003470:Culture Media; D006600:Hexosephosphates; D009713:Nucleotidyltransferases; D005690:Galactose