Nonselective cation channel probably playing a role in the regulation of membrane trafficking events. Acts as Ca(2+)-permeable cation channel with inwardly rectifying activity (PubMed:19940139, PubMed:19885840). May activate ARF6 and be involved in the trafficking of GPI-anchored cargo proteins to the cell surface via the ARF6-regulated recycling pathway (PubMed:17662026). May play a role in immune processes. In adaptive immunity, TRPML2 and TRPML1 may play redundant roles in the function of the specialized lysosomes of B cells (By similarity). In the innate immune response, may play a role in the regulation of chemokine secretion and macrophage migration (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). Channel activity is reduced by low extracellular/lumenal pH level (PubMed:19940139). Forms homooligomeric complexes; probably tetrameric (By similarity). Can heterooligomerize with MCOLN1; heteromeric assemblies have different channel properties as compared to the respective homooligomers and may be tissue-specific (PubMed:19885840). Interacts with TMEM176A (PubMed:25130899). Localizes to recycling endosomes in activated macrophages and microglia. The most N-terminal extracellular/lumenal domain (referred to as I-II linker or polycystin-mucolipin domain) contributes to a structure with a four-fold rotational symmetry in a tetrameric assembly; the structure contains a central highly electronegative pore with a 14 A diameter. The pore is critical for Ca(2+) and pH regulation. The protruding structure formed by the I-II linkers may contain all the interaction sites with lipids and proteins in the endolysosomal lumen. Belongs to the transient receptor (TC 1.A.4) family. Polycystin subfamily. MCOLN2 sub-subfamily. Truncated C-terminus.