RpH-ILV is a genetically encoded ratiometric pH sensor that is targeted to a sub-population of lysosomes. RpH-ILV consists of the Homo sapiens TMEM192 gene (HGNC:26775) into which two fluorophores have been inserted: pHluorin (pH-sensitive) is inserted in the first luminal domain, and mCherry is inserted in the second luminal domain. In addition, the cytosolic C-terminus of the TMEM192 protein has been truncated. The RpH-ILV protein is targeted to the sub-population of lysosomes that contain intraluminal vesicles (ILVs) and appears to be enriched in the ILVs (FBrf0261325).