Figure 4.

Rescue of gsa7 and gsa7Δ by Gsa7p. gsa7 and gsa7Δ cells were stably transformed with pGSA7HA(BamHI). Those colonies that grew on His⁻ medium were screened for expression of Gsa7-HA by Western blotting with an antibody to the HA epitope. The nontransformed (gsa7 and gsa7Δ) and transformed (gsa7/GSA7 and gsa7Δ/GSA7) cells were then grown in methanol induction medium and adapted to glucose for 6 h. The AOX activities are presented as a percentage of the activities measured at 0 h and represent the mean ± SD of four or more determinations. The degradation of cellular proteins during nitrogen starvation was performed as described previously in MATERIALS AND METHODS. Cellular proteins were radiolabeled and then chased in starvation medium lacking histidine and nitrogen. The production of TCA-soluble radioactivity was measured at 2–24 h of chase.