The products of YCF1 and YLL015w (BPT1) cooperate for the ATP-dependent vacuolar transport of unconjugated bilirubin in Saccharomyces cerevisiae

Since bilirubin-like pigments are present in the environment as degradation products of heme-containing proteins, yeast could have developed a detoxif ying system to transport these compounds into their vacuoles. Vacuoles from Saccharomyces cerevisiae showed an ATP-dependent, saturative transport of unconjugated bilirubin (UCB) that was reduced by 60% and 40% in YCF1 and YL L015w-deleted cells, respectively; the double deletant showed no UCB uptake . Conversely, the transport of bile acids (taurocholate) was comparable in wild and deleted stains. These data identify YCF1 and YLL015w, named BPT1 ( (B) under bar ile (P) under bar igment Transporter), as the genes responsib le for ATP-dependent UCB transport in yeast. Since YCF1 and YLL015w are rat her homologous with multidrug resistant proteins (MRPs), they also suggest the involvement of this class of transporters in the ATP-dependent transpor t of unconjugated bilirubin, Copyright (C) 2000 John Wiley & Sons, Ltd.