FIGURE 4:

Nitrogen starvation is sufficient to induce the accumulation of a similar set of SDS-insoluble proteins. (A) Wild-type and pep4Δ cells expressing a GFP-Atg8 fusion protein were harvested after 8 h of nitrogen starvation. Protein extracts from 1 × 10⁷ cells were subjected to SDS–PAGE and blotted for GFP. GFP-Atg8 and free GFP are indicated. The amount of free GFP as a percentage of the total GFP is shown for each sample. (B) Insoluble protein from wild-type and pep4Δ cells during logarithmic growth and after 8 h of nitrogen starvation were extracted and compared as previously described. Material from 8 × 10⁷ cells was loaded into each lane. (C) Insoluble proteins were extracted as previously described and compared between cells growing logarithmically (SC), cells nitrogen starved for 8 h (SC-N), postmitotic cells (young), and cells aged postmitotically for 48 h (aged). Two biological replicates (1, 2) of each treatment are shown. Material from 8 × 10⁷ cells was loaded from each sample.