Nonselective ligand-gated cation channel probably playing a role in the regulation of membrane trafficking events . Acts as a Ca(2+)-permeable cation channel with inwardly rectifying activity (By similarity). Mediates release of Ca(2+) from endosomes to the cytoplasm, contributes to endosomal acidification and is involved in the regulation of membrane trafficking and fusion in the endosomal pathway (By similarity). Does not seem to act as mechanosensory transduction channel in inner ear sensory hair cells. Proposed to play a critical role at the cochlear stereocilia ankle-link region during hair-bundle growth. Involved in the regulation of autophagy. Through association with GABARAPL2 may be involved in autophagosome formation possibly providing Ca(2+) for the fusion process (By similarity). Through a possible and probably tissue-specific heteromerization with MCOLN1 may be at least in part involved in many lysosome-dependent cellular events. Possible heteromeric ion channel assemblies with TRPV5 show pharmacological similarity with TRPML3 (By similarity).
Subcellular locations: Lysosome membrane, Early endosome membrane, Late endosome membrane, Cytoplasmic vesicle, Autophagosome membrane, Cell projection, Stereocilium membrane
Recycles between the plasma membrane and intracellular compartments by a dynamin-dependent endocytic pathway (By similarity). In the cochlea located at the base of stereocilia near the position of the ankle links (By similarity).