Two-pore channel 2 (TPC2) is a member of the endolysosomal ion channel family, playing critical roles in intracellular calcium signaling and endomembrane dynamics. This review provides an in-depth analysis of TPC2, covering its structural and functional properties, physiological roles, and involvement in human diseases. We discuss current experimental approaches to studying TPC2, including heterologous expression in plant vacuoles and computational modeling strategies. Particular emphasis is placed on the structural determinants of ion permeation, with a focus on the selectivity filter and the central cavity’s influence on channel kinetics. Furthermore, we explore emerging roles of TPC2 in viral infections, particularly SARS-CoV-2, and in cancer, including melanoma progression and neoangiogenesis. The inhibitory potential of natural compounds, such as naringenin, is also examined. By offering a comprehensive overview of current knowledge and methodologies, this review underscores the potential of TPC2 as a promising pharmacological target in both infectious and neoplastic diseases.

Two-pore channels (TPCs) are evolutionarily conserved intracellular cation channels found in both plants and animals, where they mediate ion fluxes across endomembrane compartments. While historically the plant channel was among the first plant ion channels to be characterized, thanks to the relative ease of applying the patch-clamp technique to isolated plant vacuoles, where it is localized, the functional properties of the two main human isoforms, HsTPC1 and HsTPC2, expressed in endosomal and lysosomal membranes, were elucidated much later. In plants, TPCs are typically represented by a single isoform, exemplified by AtTPC1 in the model plant Arabidopsis thaliana, which functions as a voltage-dependent, Ca²⁺-regulated channel. The physiological role of plant TPCs is not yet fully clarified, although evidence suggests that they may contribute to systemic signaling and stress responses. In humans, two main isoforms, HsTPC1 and HsTPC2, are expressed in endosomal and lysosomal membranes. Human TPCs are primarily regulated by the phosphoinositide PI(3,5)P₂ and display a high selectivity for Na⁺. However, these channels also appear as a non-selective cationic conductance when activated by the potent Ca²⁺-mobilizing messenger NAADP, likely through interaction with an accessory protein. Functionally, human TPCs are involved in endolysosomal trafficking, membrane fusion, and intracellular signaling, with emerging roles in immunity, metabolism, and disease. Overall, TPCs represent key components of intracellular ion homeostasis and cellular physiology; however, their precise regulatory mechanisms and integrated physiological roles remain only partially understood and, in several respects, are still elusive.