ATP6AP1
Description
The ATP6AP1 (ATPase H+ transporting accessory protein 1) is a protein-coding gene located on chromosome X.
The human gene ATP6AP1 encodes the S1 subunit of the enzyme V-type proton ATPase. This gene encodes a component of a multisubunit enzyme (1 mDa MW) that mediates acidification of eukaryotic intracellular organelles. Vacuolar ATPase (V-ATPase) is composed of a cytosolic, V1, (site of the ATP catalytic site) and a transmembrane, V0, domain. V-ATPase dependent organelle acidification is necessary for such intracellular processes as protein sorting, zymogen activation, and receptor-mediated endocytosis. The encoded protein of this gene is approximately 45 kD and may assist in the V-ATPase-mediated acidification of neuroendocrine secretory granules.
ATP6AP1 is an accessory subunit of the V-type ATPase protein pump, essential for acidifying the lumen of secretory vesicles. It guides V-type ATPase to specific cellular compartments like neuroendocrine secretory vesicles and osteoclast ruffled borders, controlling its activity. ATP6AP1 participates in membrane trafficking and Ca(2+)-dependent membrane fusion, potentially contributing to V-type ATPase complex assembly. In aerobic conditions, it plays a role in intracellular iron homeostasis, activating Fe(2+) prolyl hydroxylase (PHD) enzymes, leading to HIF1A hydroxylation and subsequent proteasomal degradation. Within the islets of Langerhans cells, it may regulate the acidification of dense-core secretory granules.
ATP6AP1 is also known as 16A, ATP6IP1, ATP6S1, Ac45, CF2, VATPS1, XAP-3, XAP3.
