The development and validation of electrophysiological assays to study TRPML1 is important to understand the function and pharmacology of the channel. We used a TRPML1 variant that lacks the endo-lysosomal retention sequences (TRPML1-4A), enabling the channel to express at the plasma membrane3. As such channel behaviour can be characterised by means of whole-cell patch-clamp and fluorescence-based techniques.