Tax4 regulates phosphatidylinositol 4,5-bisphosphate levels in the cell by activating the PtdIns phosphatase Inp51p (Morales-Johansson et al. 2004). It localizes to the PAS upon triggering of autophagy and mediates the recruitment of Atg17 to the PAS, thus affecting the early stages of autophagy. Interestingly, Tax4 is required for the normal expression of VPS51, one of the subunits of the GARP complex (Bugnicourt et al. 2008), suggesting an interaction between Tax4 and the GARP complex specifically in autophagy. We hypothesize that the overexpression of COG4 or TAX4 can either provide more membrane to the PAS to form the autophagosome, or recruit more regulators such as Atg17 to increase the extent of autophagy, in the arl1Δ strain background.