Nicotinic acid adenine dinucleotide phosphate (NAADP) binding protein required for NAADP-evoked intracellular calcium release (PubMed:33758061, PubMed:33758062). Confers NAADP-sensitivity to the two pore channels (TPCs) complex (PubMed:33758061). Enables NAADP to activate Ca(2+) release from the endoplasmic reticulum through ryanodine receptors (PubMed:33758062). (Microbial infection) Involved in the endolysosomal trafficking of coronaviruse SARS-CoV-2. Monomer (PubMed:33758062). Dimer (PubMed:33758062). Interacts with TPCN1 (PubMed:33758061). Colocalizes with type 1 ryanodine receptor (RYR1). Expressed in liver, kidney, prostate, testis and uterus. Up-regulated in squamous cell carcinoma (SCC) adenocarcinoma (AC), adenosquamous cell carcinoma (ASCC), bronchioalveolar carcinoma (BAC), breast and uterus tumors. Belongs to the JUPITER family.