ATP13A4 is a P5-type transport ATPase that functions as a polyamine transporter involved in cellular calcium homeostasis and neurodevelopment 12. The protein localizes to the endoplasmic reticulum and endosomal compartments, where it undergoes autophosphorylation characteristic of P-type ATPases 32. ATP13A4 mediates polyamine transmembrane transport, with overexpression significantly increasing polyamine uptake in breast cancer cells 1. The protein also regulates intracellular calcium levels, as overexpression causes increased cellular calcium concentrations 2. ATP13A4 shows tissue-specific expression, being particularly abundant in brain and epithelial glandular cells, with high expression during embryonic neurogenesis (days 15-17) 32. Disease relevance includes association with autism spectrum disorders, where an E646D mutation disrupts calcium regulation function 2. The gene is also linked to language delays when disrupted by chr3 inversions and shows increased expression in schizophrenia brain tissue 45. In cancer, ATP13A4 upregulation drives elevated polyamine transport systems, making it a potential therapeutic target for polyamine transport inhibitors 1.