Regulation of the inositol transporter Itr1p by hydrogen peroxide in Saccharomyces cerevisiae.

Myo-inositol is a precursor of several membrane phospholipids and sphingolipids and plays a key role in gene regulation in Saccharomyces cerevisiae (S. cerevisiae). Here, we tested whether HO was affecting the levels of the inositol transporters and thus inositol uptake. In S. cerevisiae cells adapted to HO Itr1-GFPp accumulated in the plasma membrane until 20 min, concomitantly with an inhibition of its internalization. Exposure to HO did not alter Itr2-GFPp cellular levels and induced only an 8% decrease at 10 min in the plasma membrane. Therefore, decreased inositol intracellular levels are not caused by decreased levels of inositol transporters in the plasma membrane. However, results show that HO adaptation affects Itr1p turnover and, consequently, HO-adapted yeast cells display an inositol transporter phenotype comparable to cells grown in the absence of inositol in growth medium, i.e. accumulation in the plasma membrane and decreased degradation.