The maltose transport capacity of fermenting Saccharomyces cerevisiae
rapidly decreases when protein synthesis is impaired. Using polyclonal
antibodies against a recombinant maltose transporter-protein we measu
red the cellular content of the transporter along this inactivation pr
ocess. Loss of transport capacity was paralleled by a decrease of cros
s-reacting material which suggests degradation of the transporter. We
also show that in ammonium-starved cells the half-life of the maltose
transporter is 1.3 h during catabolism of glucose and > 15 h during ca
tabolism of ethanol.