The function of Ensembl gene identifier ENSG00000146409 (SLC18B1, solute carrier family 18 member B1) is as follows. Proton-coupled polyamine antiporter involved in the translocation of polyamines from cytosol into secretory vesicles prior to their release via exocytosis. Uses the electrochemical proton gradient generated by a V-type proton-pumping ATPase to couple the efflux of protons with the uptake of a polyamine molecule (PubMed:25355561). Facilitates vesicular storage of spermine and spermidine in astrocytes with an impact on glutamatergic neuronal transmission and memory formation (By similarity) (PubMed:25355561). Upon antigen stimulation, regulates polyamine accumulation and release in mast cell secretory granules, which in turn potentiates mast cell degranulation and histamine secretion (By similarity). .