Involved in vesicular storage and exocytosis of ATP. May accumulate ATP and other nucleotides in secretory vesicles such as adrenal chromaffin granules and synaptic vesicles. Predominantly expressed in adrenal gland, brain and thyroid. The disease is caused by variants affecting the gene represented in this entry. Belongs to the major facilitator superfamily. Sodium/anion cotransporter family. Truncated C-terminus.