Quantitative Assay of Macroautophagy Using Pho8△60 Assay and GFP-Cleavage Assay in Yeast

It is intrinsically difficult to directly measure a specific protein reduction that is mediated by nonselective autophagy, because the degradation proceeds at a relatively slow pace, and the residual nondegraded part becomes the background. Several methods for measuring nonselective autophagy have been reported in the past. One classical simple method is called bulk degradation assay, which measures the release of degraded amino acids after radioisotope labeling of the total cellular proteins. In 1995, we developed a quantitative Pho8△60 assay in the yeast, Saccharomyces cerevisiae, for studying autophagy, which is widely used for its advantages that are described in the following sections. Another method used in recent times is the GFP-based processing assay in yeast. We will describe these two methods in this chapter.