Enables enzyme binding activity and serotonin:sodium symporter activity. Involved in cellular response to lithium ion; regulation of ion transport; and serotonin uptake. Located in cytoplasm. Human ortholog(s) of this gene implicated in bipolar disorder and schizophrenia. Orthologous to human SLC18A1 (solute carrier family 18 member A1). [provided by Alliance of Genome Resources, Apr 2022]