title: Uptake of putrescine and spermidine by Gap1p on the plasma membrane in Saccharomyces cerevisiae.
abstract: It has been reported that Gap1p on the plasma membrane of Saccharomyces cerevisiae can catalyze the uptake of many kinds of amino acids. In the present study, we found that Gap1p also catalyzed the uptake of putrescine and spermidine, but not spermine. The Km and Vmax values for putrescine and spermidine were 390 and 21 microM, and 4.6 and 0.59 nmol/min/mg protein, respectively. The uptake of putrescine was strongly inhibited by basic amino acids, lysine, arginine, and histidine, whose Ki values were 25-35 microM. Thus, it is deduced that spermidine and basic amino acids have almost the same affinity for Gap1p. When the concentrations of amino acids in the medium were reduced to one-third and 0.5 mM putrescine or 0.1 mM spermidine was added to the medium, accumulation of putrescine or spermidine by Gap1p was observed. Furthermore, when yeast was transformed with the GAP1 gene and cultured in the presence of 60 mM putrescine, cell growth was inhibited through overaccumulation of putrescine. GAP1 mRNA was found to be induced by polyamines. This is the first report of the identification, at a molecular level, of a polyamine uptake protein on the plasma membrane in eukaryotes.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Uemura
authors.forename: Keiko
authors.initials: K
authors.lastname: Kashiwagi
authors.forename: Kazuei
authors.initials: K
authors.lastname: Igarashi
mesh_terms: D026905:Amino Acid Transport Systems / Q000378:metabolism*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D008565:Membrane Proteins / Q000378:metabolism; D008657:Metabolic Clearance Rate; D011700:Putrescine / Q000008:administration & dosage / Q000493:pharmacokinetics*; D011994:Recombinant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D013095:Spermidine / Q000008:administration & dosage / Q000493:pharmacokinetics*; D013096:Spermine / Q000008:administration & dosage / Q000493:pharmacokinetics
chemical_list: D026905:Amino Acid Transport Systems; C491145:GAP1 protein, S cerevisiae; D008565:Membrane Proteins; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D013096:Spermine; D013095:Spermidine; D011700:Putrescine