ATPase which acts as a lysosomal polyamine exporter with high affinity for spermine (PubMed:31996848). Also stimulates cellular uptake of polyamines and protects against polyamine toxicity (PubMed:31996848). Plays a role in intracellular cation homeostasis and the maintenance of neuronal integrity (PubMed:22186024). Contributes to cellular zinc homeostasis (PubMed:24603074). Confers cellular protection against Mn(2+) and Zn(2+) toxicity and mitochondrial stress (PubMed:26134396). Required for proper lysosomal and mitochondrial maintenance (PubMed:22296644, PubMed:28137957). 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 (PubMed:25392495, PubMed:24603074). Plays a role in lipid homeostasis (PubMed:31132336). ATP + H2O + spermidine(out) = ADP + H(+) + phosphate + spermidine(in) ATP + H2O + spermine(out) = ADP + H(+) + phosphate + spermine(in) Accumulates in an inactive autophosphorylated state (PubMed:26134396). The presence of spermine results in a dose-dependent reduction in autophosphorylation (PubMed:31996848). Interacts with MYCBP2; the interaction inhibits the ubiquitination of TSC2 by MYCBP2 (PubMed:27278822). Interacts with HDAC6; the interaction results in recruitment of HDAC6 to lysosomes to promote CTTN deacetylation (PubMed:30538141). Expressed in brain; protein levels are markedly increased in brain from subjects with Parkinson disease and subjects with dementia with Lewy bodies. Detected in pyramidal neurons located throughout the cingulate cortex (at protein level). In the substantia nigra, it is found in neuromelanin-positive dopaminergic neurons (at protein level). 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) (PubMed:26134396). PA and PI(3,5)P2 are required for the protective effect against mitochondrial stress (PubMed:26134396). Autophosphorylated (PubMed:26134396, PubMed:28137957). 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+) (PubMed:26134396). The presence of spermine results in a dose-dependent reduction in autophosphorylation (PubMed:31996848). The disease is caused by variants affecting the gene represented in this entry. KRS has also been referred to as neuronal ceroid lipofuscinosis 12 (CLN12), due to neuronal and glial lipofuscin deposits detected in the cortex, basal nuclei and cerebellum of some patients. The disease is caused by variants affecting the gene represented in this entry. Belongs to the cation transport ATPase (P-type) (TC 3.A.3) family. Type V subfamily.