Skip to main content
. 2021 Jun 2;14(11):3019. doi: 10.3390/ma14113019

Figure 3.

Figure 3

Monitoring of autophagy progression by tandem or triple FPs with different pH-sensitivity (a) RFP-GFP-LC3 is a tandem FP-tagged LC3 sensor consisting a pH-sensitive GFP and a pH-stable RFP. Both green and red signals are expected in autophagosomes, while green signal disappears in autolysosomes. (b) GFP-LC3-RFP-LC3∆G is composed of GFP-LC3 and RFP-LC3∆G linked by a substrate for an autophagy initiating protease Atg4. When autophagy is induced, the activated Atg cleaves the substrate, generating GFP-LC3 and RFP-LC3∆G. The released GFP-LC3 can be localized at autophagic vesicles, while the RFP-LC3∆G remains in the cytosol serving as an internal control for GFP-LC3. (c) Red-green-blue-LC3 (RGB-LC3) is composed of three colors of FPs with different pH-sensitivity: a highly pH-sensitive superecliptic pHluourin (SEP, pKa = 7.2), a pH-stable mTagBFP2 (pKa = 2.7), and mApple (pKa = 6.5) with intermediate pKa and pH-sensitivity. The RGB-LC3 sensor allows for the monitoring of different stages of autophagy.