Figure 9. Hypoxia down-regulates amino acid transporters.

Cells grown in minimal medium as in Fig. 1 were assayed for expression of amino acid transporters (A), select amino acids (B) and lacZ reporter activities (C). A) Immunoblot analysis of cells expressing TAP tagged versions of Agp1p (90.7 kDa), Bap2p (88.1 kDa) and Gnp1 (94,6 kDa). Arrows indicate positions of Agp1p and Gnp1p. Results are representative of four experimental trials. B) Levels of the indicated amino acids were measured from triplicate cell samples by ion exchange chromatography. Error bars represent standard deviation. Fold change represents values from hypoxia grown samples over that of control aerobic cells. C) Cells transformed with plasmids for expressing lacZ under the control of the AGP1 (top) or OLE1 (bottom) promoter were assayed for ß-galactosidase as in Materials in Methods. Results represent the averages of 2–3 independent transformants and error bars represent range. Values shown are in Miller units.