M‐Track signal enrichment system. Illustrations explaining the M‐Track signal enrichment systems used: (A) Atg13–protA–H3 yeast cells expressing plasmid‐based HKMT‐tagged Atg1, Atg17, Pbs2 or an empty plasmid (pRS315) were grown to mid‐log phase and TCA precipitated. Extracts were analysed by anti‐me3K9 and anti‐protA western blotting. (B) Wild‐type, Atg17–H3 or Atg1–H3 yeast strains containing HKMT‐tagged Atg13, Pbs2 or an empty plasmid (pRS315) were grown to mid‐log phase and treated with rapamycin for 1 h, which induces autophagy and possibly increases the interaction of proteins analysed. Extracts were prepared and analysed as described in (A). (C) Wild‐type, Atg17–protA–H3 or Atg1–protA–H3 yeast strains containing HKMT‐tagged Atg2, Atg13 or an empty plasmid (pRS315) were grown to mid‐log phase and treated with rapamycin for 1 h. Extracts were prepared and protA–H3 tagged proteins were isolated on IgG magnetic beads, followed by TEV cleavage. The protA–H3 tags bound on the beads were analysed by western blotting.