Figure 5.

Axl1p abundance is controlled by glucose and Snf1p, and Axl1p is an inhibitor of invasive growth. (A) Axl1p is absent in filamentous cells. Western blot of protein extracts from wild-type cells containing p151 (SY3718) incubated on SCD-URA (+Glu) or SC-URA (−Glu) solid agar medium for 16 h at 25°C and probed with antibodies against HA (to detect Axl1p-HA) or Dpm1p (see MATERIALS AND METHODS). (B) Abundance of Axl1p correlates with the culture growth cycle. Wild-type cells containing p151 (SY3718) were grown through a growth cycle in SCD-URA liquid medium at 30°C, and protein extracts were harvested from cells at the times indicated. Quantitation of Western blots of Axl1p levels (adjusted to Dpm1p levels) is shown (filled circles). Optical density at 600 nm is also shown (open squares). (C) Decrease in Axl1p abundance upon a shift to glucose-limited medium is dependent upon Snf1p. Wild-type cells containing p151 (SY3718) were grown to early log phase and shifted to SCD-URA (open squares, +Glu) or SC-URA (open triangles, −Glu) medium. A snf1 mutant containing p151 (SY3720) was grown in the same way (closed circles, −Glu). Quantitation of Western blots of Axl1p levels (adjusted to Dpm1p levels) is shown. (D) Hyperinvasive growth in axl1 mutants. Equal concentrations of wild-type (SY3687), axl1 (SY3721), axl1 bud8 (SY3722), and bud8 (SY3689) cells were spotted onto YPD medium and incubated for 2 d at 30°C. The plate was photographed (left), washed, and photographed again (right). The colonies shown are all from the same plate. (E) Overproduction of Axl1p prevents invasive growth. Wild-type (SY3687) and GAL1-AXL1 (↑ AXL1, SY3723) cells were grown to saturation in YPGal medium, and equal concentrations of cells were spotted onto YPGal medium for 2 d at 30°C. The plates were photographed (left), washed, and photographed again (right).