L-[U-14C] lactate binding to a 43 kDa protein in plasma membranes of Candida utilis.
To identify the putative lactate transporter protein of Candida utilis, plasma membranes from cells grown either on lactic acid (presence of lactate proton symport) or glucose (absence of lactate proton symport) were incubated with L-[U-14C]lactic acid and the membrane proteins were then separated by SDS-PAGE. A well-defined peak of radioactivity occurred in the lane of the gel containing plasma membrane proteins from lactic-acid-grown cells but not from glucose-grown cells. Binding was inhibited by unlabelled pyruvate and lactate, whereas succinate and citrate were not inhibitory. The monocarboxylate transporter inhibitor of animal cells, 4,4'-diisothiocyanatostilbene-2,2'-disulfonate, competitively inhibited the lactate proton symport in the whole yeast and also inhibited lactate binding to proteins of isolated plasma membranes. The polypeptide pattern of plasma membranes from lactic-acid-grown cells revealed a 43 kDa polypeptide associated with the peak of labelled lactate. Altogether the results suggest that this polypeptide is either the lactate transporter or a component of it.
Gerós
Hernâni
H
Centro de Ciências do Ambiente, Departamento de Biologia, Universidade do Minho, 4710-057 Braga, Portugal1.
Baltazar
Fátima
F
Centro de Ciências do Ambiente, Departamento de Biologia, Universidade do Minho, 4710-057 Braga, Portugal1.
Cássio
Fernanda
F
Centro de Ciências do Ambiente, Departamento de Biologia, Universidade do Minho, 4710-057 Braga, Portugal1.
Leão
Cecı Lia
CL
Centro de Ciências do Ambiente, Departamento de Biologia, Universidade do Minho, 4710-057 Braga, Portugal1.
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D001692:Biological Transport; D002175:Candida / Q000254:growth & development / Q000378:metabolism*; D002250:Carbon Radioisotopes / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005656:Fungal Proteins / Q000378:metabolism; D007773:Lactates / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*
D002250:Carbon Radioisotopes; D002352:Carrier Proteins; D005656:Fungal Proteins; D007773:Lactates; D008565:Membrane Proteins; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid