What is the pH inside lysosomes?

Under physiological condition, the pH inside lysosomes is around 4.5.

We offer two unique pH probes, Protonex™ Green 500 and Protonex™ Red 600, for monitoring acidic organelles such as endosomes and lysosomes. Both probes demonstrate pH-dependent fluorescence. As the pH decreases from neutral to acidic, the fluorescence intensity increases.