Nomenclature	TRPML1	TRPML2	TRPML3
HGNC, UniProt	MCOLN1, Q9GZU1	MCOLN2, Q8IZK6	MCOLN3, Q8TDD5
Activators	TRPML1Va: Constitutively active, current potentiated by extracellular acidification (equivalent to intralysosomal acidification)	TRPML2Va: Constitutively active, current potentiated by extracellular acidification (equivalent to intralysosomal acidification)	TRPML3Va: Constitutively active, current inhibited by extracellular acidification (equivalent to intralysosomal acidicification), Wild type TRPML3: Activated by Na+-free extracellular (extracytosolic) solution and membrane depolarization, current inhibited by extracellular acidification (equivalent to intralysosomal acidicification)
Channel Blockers (IC50)	–	–	Gd3+
Functional characteristics	TRPML1Va: γ = 40 pS and 76-86 pS at very negative holding potentials with Fe2+ and monovalent cations as charge carriers, respectively; conducts Na+≅ K+>Cs+ and divalent cations (Ba2+>Mn2+>Fe2+>Ca2+> Mg2+> Ni2+>Co2+> Cd2+>Zn2+>>Cu2+) protons; monovalent cation flux suppressed by divalent cations (e.g. Ca2+, Fe2+); inwardly rectifying	TRPML1Va: Conducts Na+; monovalent cation flux suppressed by divalent cations; inwardly rectifying	TRPML3Va: γ = 49 pS at very negative holding potentials with monovalent cations as charge carrier; conducts Na+ > K+ > Cs+ with maintained current in the presence of Na+, conducts Ca2+ and Mg2+, but not Fe2+, impermeable to protons; inwardly rectifying Wild type TRPML3: γ = 59 pS at negative holding potentials with monovalent cations as charge carrier; conducts Na+ > K+ > Cs+ and Ca2+ (PCa/PK ≅ 350), slowly inactivates in the continued presence of Na+ within the extracellular (extracytosolic) solution; outwardly rectifying