ATPase which acts as a lysosomal polyamine exporter with high affinity for spermine (By similarity). Also stimulates cellular uptake of polyamines and protects against polyamine toxicity (By similarity). Plays a role in intracellular cation homeostasis and the maintenance of neuronal integrity (By similarity). Contributes to cellular zinc homeostasis (By similarity). Confers cellular protection against Mn(2+) and Zn(2+) toxicity and mitochondrial stress (By similarity). Required for proper lysosomal and mitochondrial maintenance (By similarity). Regulates the autophagy-lysosome pathway through the control of SYT11 expression at both transcriptional and post-translational levels (PubMed:27278822). Facilitates recruitment of deacetylase HDAC6 to lysosomes to deacetylate CTTN, leading to actin polymerization, promotion of autophagosome-lysosome fusion and completion of autophagy (PubMed:30538141). Promotes secretion of exosomes as well as secretion of SCNA via exosomes (By similarity). Plays a role in lipid homeostasis (By similarity). ATP + H2O + spermidine(out) = ADP + H(+) + phosphate + spermidine(in) ATP + H2O + spermine(out) = ADP + H(+) + phosphate + spermine(in) Accumulates in an inactive autophosphorylated state. The presence of spermine results in a dose-dependent reduction in autophosphorylation. Interacts with MYCBP2; the interaction inhibits the ubiquitination of TSC2 by MYCBP2 (By similarity). Interacts with HDAC6; the interaction results in recruitment of HDAC6 to lysosomes to promote CTTN deacetylation (By similarity). The N-terminal region is required for targeting to late endosomes/lysosomes. It does not traverse the membrane but contains a membrane-embedded intramembrane domain and interacts with the lipids phosphatidic acid (PA) and phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2). PA and PI(3,5)P2 are required for the protective effect against mitochondrial stress. Autophosphorylated. Accumulates in an inactive autophosphorylated state and autophosphorylation is stimulated by phosphatidic acid and phosphatidylinositol 3,5-bisphosphate but not by Mn(2+) or Zn(2+). The presence of spermine results in a dose-dependent reduction in autophosphorylation. No visible phenotype at 4 months (PubMed:30538141). At 10 months, gradual loss of body weight, increased liver size and reduced adipose tissue mass (PubMed:30538141). These phenotypes further progress to 18 months with significantly smaller body size, hepatomegaly, increased intracellular vacuolation in liver tissues, markedly reduced adipose tissue with small adipocytes, accumulation of autophagy receptor Sqstm1/p62 and autophagy-related protein LC3 in liver, and accumulation of ubiquitinated insoluble proteins (PubMed:30538141). Belongs to the cation transport ATPase (P-type) (TC 3.A.3) family. Type V subfamily.