FIGURE 3.
Atg1 self-association required the presence of the Atg13 protein. A, the level of the Atg1-Atg1 complex was greatly diminished in atg13Δ cell extracts. The relative level of the Atg1 self-interaction was assessed in the indicated strains expressing the full-length Atg1-myc3 with or without the full-length HA3-Atg1. The HA3-Atg1 was precipitated on an α-HA affinity resin, and the relative amount of the associated Atg1-myc3 was assessed by Western blotting with an α-myc antibody. B, the relative level of the Atg1 self-association was elevated in cells overexpressing (OE) Atg13. The values shown below the top panel indicate the relative level of Atg1-myc protein present in the co-immunoprecipitation reaction. The Western blot signal was quantified with the ImageJ program and normalized to that present in the vector (Vec) control lane. C, the kinase-defective Atg1K54A variant exhibited a normal self-interaction. The Atg1 self-association was examined in cells expressing myc- and HA-tagged versions of either the wild-type Atg1 or the kinase-defective variant, Atg1K54A, as indicated.