Figure 5.

Yeast vacuoles accumulated a high level of tyrosine, isoleucine, and leucine in the absence of Atg22 and/or Avt3/Avt4. The wild-type (SEY6210), atg22Δ (ZFY6), avt3Δ avt4Δ (ZFY20), and avt3Δ avt4Δ atg22Δ (ZFY22) cells were grown in YPD medium and harvested at log phase. The preparation of vacuolar amino acid pools and analysis of amino acid composition are described in Materials and Methods. The results represent the mean and SD of three experiments. The amino acid concentration was normalized to the highest concentration of arginine among three experiments. The results are displayed as the ratio to wild type (A), the absolute values expressed as nanomoles/10⁸ cells (B), and the difference from wild type for tyrosine, isoleucine, leucine, valine, methionine, and phenylalanine for the wild-type, atg22Δ (I), avt3Δ avt4Δ (II), and avt3Δ avt4Δ atg22Δ (III) strains (C). Tyrosine, isoleucine, and leucine accumulated in the mutants, compared with the controls valine, methionine, and phenylalanine. The table lists the vacuolar amino acid levels shown in the graph in B.