Vacuolar-type H+-ATPase (V-ATPase) (V-ATPase)

Vacuolar-type H+-ATPase (V-ATPase) is a multi-subunit enzyme complex that functions as an ATP-driven proton pump, primarily responsible for the acidification of endosomes, lysosomes, and other intracellular organelles [8, 17, 23]. By transporting protons from the cytoplasm into the organelle lumen, V-ATPase creates the acidic environment necessary for various biological processes, including receptor-ligand dissociation, protein degradation, and vesicular trafficking [8, 21, 24]. Dysregulation of endosomal pH is implicated in numerous diseases; for instance, many viruses (such as SARS-CoV-2 and Influenza) exploit the acidic endosomal environment for membrane fusion and entry into the host cell [1, 12, 15]. In cancer, V-ATPase is often overexpressed or relocated to the plasma membrane, contributing to an acidic tumor microenvironment that promotes invasion and drug resistance [3, 8, 23]. Therapeutic strategies targeting endosomal acidification include direct V-ATPase inhibitors like bafilomycin A1 and lysosomotropic agents like chloroquine, which neutralize the pH gradient [11, 12, 15, 19]. However, the essential housekeeping role of V-ATPase across multiple tissues presents significant challenges for achieving therapeutic selectivity and minimizing systemic toxicity [8, 23].

Other names

Endosomal acidificationEndosomal pH regulationVacuolar proton pumpH+-transporting ATPaseV-type ATPase

Drugs targeting endosomal acidification primarily act by either directly inhibiting the V-ATPase enzyme complex (e.g., bafilomycin A1) to prevent proton pumping, or by acting as lysosomotropic weak bases (e.g., chloroquine) that accumulate in acidic compartments and neutralize the pH gradient [11, 12, 15]. These actions disrupt pH-dependent processes such as viral membrane fusion, receptor-ligand dissociation, and lysosomal enzyme activity [1, 19].