Evidence for a mobile membrane carrier mediating the uphill monosaccharide transport in the yeastRhodotorula gracilis is based on two types of observations: (1) Countertransport was found with(14)C-labelledD-xylose,L-xylose,L-rhamnose and withL-rhamnose in a cell suspension preincubated with unlabelledD-xylose. This finding indicates, moreover, that both the hexoses and the pentose share the same membrane carrier. (2) The mobility of occupied carrier molecules is higher than that of free carrier molecules. This conclusion has been drawn from: (a) comparison of the initial rates of uptake of a labelled sugar into cells preincubated in the absence and in the presence of unlabelled sugar; (b) comparison on the half-saturation constant of transport with the dissociation constant of the sugar-carrier complex; and (c) comparison of the initial rates of efflux of a labelled sugar into sugar-free and sugar-containing medium.

Laboratory for Cell Membrane Transport Institute of Microbiology Czechoslovak Academy of Sciences Prague Czechoslovakia

Zobrazit více v PubMed

J Theor Biol. 1963 Sep;5(2):288-305 PubMed

Biochim Biophys Acta. 1967 Feb 1;135(1):112-9 PubMed

J Biol Chem. 1952 Mar;195(1):19-23 PubMed

Biophys J. 1965 Jul;5(4):417-23 PubMed

Folia Microbiol (Praha). 1968;13(3):197-204 PubMed

Biochim Biophys Acta. 1965 Jul 22;102(2):410-22 PubMed

Biophys J. 1965 Jul;5(4):487-509 PubMed

Biochim Biophys Acta. 1964 Jan 27;79:177-200 PubMed

Folia Microbiol (Praha). 1968;13(3):205-11 PubMed

J Biol Chem. 1966 May 25;241(10):2200-11 PubMed