The function of MCOLN3 (mucolipin TRP cation channel 3, ENSG00000055732) is as follows. Nonselective 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 (PubMed:18369318, PubMed:19497048, PubMed:19522758, PubMed:19885840, PubMed:29106414). 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 (PubMed:21245134). Also permeable to Mg(2+), Na(+) and K(+) (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 (By similarity). Involved in the regulation of autophagy (PubMed:19522758). 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 (PubMed:19885840). Possible heteromeric ion channel assemblies with TRPV5 show pharmacological similarity with TRPML3 (PubMed:23469151). {ECO:0000250|UniProtKB:Q8R4F0, ECO:0000269|PubMed:18369318, ECO:0000269|PubMed:19497048, ECO:0000269|PubMed:19522758, ECO:0000269|PubMed:19885840, ECO:0000269|PubMed:20378547, ECO:0000269|PubMed:21245134, ECO:0000269|PubMed:23469151, ECO:0000269|PubMed:29106414, ECO:0000305}.