Comprehensive Research Report: ATP6V0E1 (V-type Proton ATPase Subunit e1) in Homo sapiens Falcon

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Comprehensive Research Report: ATP6V0E1 (V-type Proton ATPase Subunit e1) in Homo sapiens

Executive Summary

ATP6V0E1 (UniProt: O15342) encodes the e1 subunit of the V-type proton ATPase (V-ATPase), a multi-subunit rotary proton pump essential for acidifying intracellular organelles in eukaryotic cells (wang2020structuresofa pages 1-3, wang2020structuresofa pages 3-5). As a structural component of the membrane-embedded Vo domain, ATP6V0E1 contributes to the proton-translocating machinery that couples ATP hydrolysis to the generation of acidic environments in lysosomes, endosomes, the trans-Golgi network, and synaptic vesicles (wang2020structuresofa pages 3-5, eaton2021theh+atpase(vatpase) pages 1-5).

Characteristic Summary
Gene name ATP6V0E1 (human gene encoding V-type proton ATPase subunit e1) (wang2020structuresofa pages 1-3, wang2020structuresofa pages 3-5)
UniProt ID O15342
Protein name V-type proton ATPase subunit e1 / ATPase H+-transporting V0 subunit e1 (wang2020structuresofa pages 3-5, chen2024thedifferentroles pages 1-2)
Protein family V-ATPase e1/e2 subunit family; the e subunit is a conserved component of the membrane-embedded V0/Vo sector (wang2020structuresofa pages 1-3, eaton2021theh+atpase(vatpase) pages 1-5)
Complex membership V-ATPase Vo domain; in the human complex, the Vo region comprises subunits a1, d1, e1, RNaseK (f), c, c'', ATP6AP1, ATP6AP2 (wang2020structuresofa pages 3-5)
Molecular function Structural component of the proton-translocating Vo domain; subunit e is positioned adjacent to the C-terminal domain of subunit a and the c-ring, contributing to organization of the membrane proton channel rather than catalyzing ATP hydrolysis directly (wang2023structuralbasisof pages 1-2, wang2020structuresofa pages 5-7, seidel2022theplantvatpase pages 2-3)
Specific interaction/role The membrane-embedded subunits e and f/RNaseK bind the C-terminal domain of subunit a, a key structural arrangement for Vo assembly and proton translocation (wang2023structuralbasisof pages 1-2, seidel2022theplantvatpase pages 2-3)
Post-translational modifications N-glycosylation at N70 on the luminal side of human subunit e; this glycosylation is discussed as important for folding, trafficking, localization, and/or stability of the V-ATPase complex (wang2020structuresofa pages 7-9)
Stoichiometry in complex 1 copy per V-ATPase complex; structural descriptions of mammalian/yeast Vo indicate a single e subunit within each assembled enzyme (wang2020structuresofa pages 1-3, wang2023structuralbasisof pages 1-2, seidel2022theplantvatpase pages 2-3)

Table: This table summarizes core identity, structure, and functional annotations for human ATP6V0E1. It is useful as a compact reference linking the gene to its Vo-domain role, structural contacts, and known modification state.

1. Protein Structure and Molecular Function

1.1 V-ATPase Complex Architecture

The V-ATPase is a large (~830 kDa) multisubunit rotary enzyme comprising two functional domains: the cytosolic V1 domain responsible for ATP hydrolysis and the membrane-embedded Vo domain that translocates protons (wang2020structuresofa pages 1-3, eaton2021theh+atpase(vatpase) pages 1-5). High-resolution cryo-electron microscopy structures of human V-ATPase at 2.9-3.1 Å resolution have elucidated the detailed organization of this complex (wang2020structuresofa pages 1-3, wang2020structuresofa pages 3-5).

The Vo domain, where ATP6V0E1 resides, consists of multiple subunits organized around a central c-ring composed of nine copies of subunit c plus one c'' subunit (wang2020structuresofa pages 3-5, wang2020structuresofa pages 7-9). The Vo complex includes subunits a1, d1, e1, RNaseK (equivalent to yeast subunit f), ATP6AP1, and ATP6AP2 in addition to the c-ring proteolipids (wang2020structuresofa pages 3-5, abbas2020structureofvatpase pages 1-2).

1.2 Role of Subunit e1 in the Vo Complex

Subunit e1, encoded by ATP6V0E1, is a small membrane-associated protein positioned adjacent to the C-terminal domain (CTD) of subunit a and the c-ring (wang2020structuresofa pages 5-7, wang2020structuresofa pages 7-9, seidel2022theplantvatpase pages 2-3). Structural studies reveal that subunit e, along with RNaseK (subunit f), binds to the a-CTD and helps organize the Vo assembly around the c-ring (wang2020structuresofa pages 5-7, wang2020structuresofa pages 7-9). This positioning is critical for maintaining the structural integrity of the proton channel and enabling efficient proton translocation.

Subunit e1 undergoes N-linked glycosylation at asparagine 70 (N70) on its luminal side, a post-translational modification that appears important for proper protein folding, trafficking, localization, and stability of the V-ATPase complex (wang2020structuresofa pages 7-9). Glycosylation of Vo subunits, including e, forms part of a luminal glycan coat that protects the V-ATPase from degradation in the acidic environments it creates (wang2020structuresofa pages 7-9).

1.3 Mechanism of Proton Translocation

The V-ATPase operates through a rotary mechanism in which ATP hydrolysis in the V1 domain drives rotation of a central rotor composed of subunits D, F, d, and the c-ring (wang2020structuresofa pages 1-3, wang2020structuresofa pages 3-5). This rotation causes conformational changes that enable proton translocation through hemi-channels formed by subunit a (wang2020structuresofa pages 3-5, seidel2022theplantvatpase pages 2-3).

In the human V-ATPase, the stoichiometry has been determined to be 3 ATP molecules hydrolyzed per 10 protons translocated (3 ATP:10 H+), reflecting the nine-membered c-ring structure (wang2020structuresofa pages 3-5, abbas2020structureofvatpase pages 1-2). Subunit e1, while not directly involved in ATP hydrolysis or forming the proton pathway, provides essential structural support that maintains the integrity and positioning of the proton channel formed by subunit a and the c-ring (wang2020structuresofa pages 5-7, wang2020structuresofa pages 7-9).

2. Subcellular Localization and Compartment-Specific Functions

V-ATPases containing ATP6V0E1 localize to multiple intracellular compartments where they establish and maintain organelle-specific pH gradients (seidel2022theplantvatpase pages 1-2, eaton2021theh+atpase(vatpase) pages 1-5, toshima2024transportmechanismsbetween pages 1-2). The specific localization of V-ATPase complexes is primarily determined by the a-subunit isoform, with four different a-subunit isoforms (a1-a4) directing V-ATPase to distinct cellular locations (abbas2020structureofvatpase pages 1-2, eaton2021theh+atpase(vatpase) pages 1-5, chen2024thedifferentroles pages 1-2).

Organelle/Compartment pH range Primary functions in that compartment Specific mechanisms
Lysosomes 4.5-5.0 Degradation of proteins, lipids, and other macromolecules; autophagy; lysosomal signaling V-ATPase pumps H+ into the lysosomal lumen using ATP hydrolysis, generating the acidic environment required for lysosomal hydrolases; lysosomal acidification also supports autophagosome-lysosome fusion and amino-acid-dependent mTORC1 signaling at the lysosomal surface (song2020theemergingroles pages 1-2, eaton2021theh+atpase(vatpase) pages 1-5, sou2024golgiphhomeostasis pages 1-3)
Late endosomes 5.0-6.0 Endosomal maturation, cargo sorting, receptor-ligand dissociation, trafficking toward lysosomes Progressive acidification by V-ATPase promotes maturation from earlier endocytic compartments, regulates Rab7-associated trafficking steps, and enables sorting of cargos en route to lysosomes (toshima2024transportmechanismsbetween pages 1-2, chen2024thedifferentroles pages 1-2)
Trans-Golgi Network / Early endosomes 6.0-6.5 Protein sorting, vesicular trafficking, glycosylation, secretory-pathway organization V-ATPase establishes mildly acidic luminal pH needed for glycosyltransferase function, cargo sorting, and trafficking between Golgi and endosomal compartments; perturbation of Golgi pH disrupts glycosylation and organelle morphology (seidel2022theplantvatpase pages 1-2, eaton2021theh+atpase(vatpase) pages 1-5, sou2024golgiphhomeostasis pages 1-3)
Synaptic vesicles Acidic; sufficient to support transmitter uptake Neurotransmitter loading and synaptic vesicle function In neurons, V-ATPase-generated proton motive force across synaptic vesicle membranes energizes vesicular neurotransmitter transporters for transmitter accumulation before exocytosis (abbas2020structureofvatpase pages 1-2, abbas2020structureofvatpase pages 2-4)
Secretory vesicles / intracellular vesicles Variable acidic lumen Secretory cargo processing, vesicle maturation, compartment-specific transport V-ATPase acidifies intracellular vesicles broadly across the secretory and endolysosomal systems, where proton gradients drive coupled transport and support vesicle-specific biochemical reactions (wang2020structuresofa pages 1-3, eaton2021theh+atpase(vatpase) pages 1-5)
Plasma membrane in specialized cells Extracellular acidification rather than organellar luminal pH Bone resorption, renal acid secretion, sperm maturation, tissue-specific extracellular acidification In selected specialized cell types, assembled V-ATPases at the plasma membrane export H+ to the extracellular space rather than into organelles; this is a property of some V-ATPase populations, though ATP6V0E1-specific localization here is not directly established (wang2020structuresofa pages 1-3, eaton2021theh+atpase(vatpase) pages 1-5)

Table: This table summarizes the main compartments where V-ATPase complexes relevant to ATP6V0E1 function operate, the characteristic pH of those compartments, and the compartment-specific processes supported by proton pumping. It is useful for linking ATP6V0E1 to endolysosomal acidification, trafficking, neurotransmission, and specialized acid-secretion contexts.

2.1 Lysosomes

In lysosomes, V-ATPases maintain the highly acidic luminal pH (4.5-5.0) required for optimal activity of lysosomal hydrolases, which degrade proteins, lipids, nucleic acids, and carbohydrates (song2020theemergingroles pages 1-2, eaton2021theh+atpase(vatpase) pages 1-5). This acidification is essential for autophagy, where autophagosomes fuse with lysosomes to form autolysosomes that digest cellular cargo (song2020theemergingroles pages 1-2). Lysosomal V-ATPases typically contain the a3 isoform, though subunit e1 can be present in various V-ATPase populations (chen2024thedifferentroles pages 1-2).

2.2 Endosomes

V-ATPases progressively acidify endosomal compartments as they mature from early endosomes (pH ~6.0) to late endosomes (pH ~5.5), enabling receptor-ligand dissociation, cargo sorting, and trafficking toward lysosomes (eaton2021theh+atpase(vatpase) pages 1-5, toshima2024transportmechanismsbetween pages 1-2, chen2024thedifferentroles pages 1-2). The a1 and a2 isoforms are enriched in early and late endosomes (abbas2020structureofvatpase pages 1-2, chen2024thedifferentroles pages 1-2). Studies in zebrafish microglia and mouse macrophages have demonstrated that the a1 subunit localizes primarily to early and late endosomes, where it regulates the transition from early to late endosomal compartments (chen2024thedifferentroles pages 1-2).

2.3 Trans-Golgi Network and Golgi Apparatus

The trans-Golgi network (TGN) and Golgi apparatus maintain a mildly acidic pH (6.0-6.5) that is essential for the activity of glycosyltransferases and proper protein glycosylation (seidel2022theplantvatpase pages 1-2, eaton2021theh+atpase(vatpase) pages 1-5, sou2024golgiphhomeostasis pages 1-3). The a2 subunit preferentially targets V-ATPase to the TGN (abbas2020structureofvatpase pages 1-2, sou2024golgiphhomeostasis pages 1-3). Disruption of Golgi pH homeostasis, such as through loss of the V-ATPase regulator GPHR, leads to abnormal protein N-glycosylation and impaired lysosomal membrane protein glycosylation, demonstrating the critical importance of proper pH control (sou2024golgiphhomeostasis pages 1-3).

2.4 Synaptic Vesicles

In neurons, V-ATPases acidify synaptic vesicles, generating the proton electrochemical gradient that drives vesicular neurotransmitter transporters to load neurotransmitters into synaptic vesicles before exocytosis (abbas2020structureofvatpase pages 1-2, abbas2020structureofvatpase pages 2-4). Rat brain V-ATPases isolated from synaptic vesicles contain the a1 isoform along with other neuron-enriched subunit isoforms including B2, C1, E1, and G2 (abbas2020structureofvatpase pages 1-2, abbas2020structureofvatpase pages 2-4).

3. Signaling and Biochemical Pathways

Beyond its canonical role in acidification, the V-ATPase participates in multiple signaling pathways and cellular processes, often serving dual roles as both a proton pump and a signaling scaffold (wang2020structuresofa pages 1-3, eaton2021theh+atpase(vatpase) pages 1-5).

Pathway name Role of V-ATPase/ATP6V0E1 Mechanism Key biological outcomes
Autophagy-lysosomal pathway Core acidification machinery of lysosomes and autolysosomes; ATP6V0E1 contributes as a Vo-domain structural subunit within the proton-translocating sector ATP hydrolysis in V1 drives proton translocation through Vo, acidifying lysosomal lumen; acidic pH activates hydrolases and supports autophagosome-lysosome fusion and cargo degradation (song2020theemergingroles pages 1-2, eaton2021theh+atpase(vatpase) pages 1-5) Proteolysis of intracellular cargo, autophagic flux, organelle turnover, prevention of aggregate accumulation; dysfunction contributes to neurodegeneration and lysosomal stress (song2020theemergingroles pages 1-2, eaton2021theh+atpase(vatpase) pages 1-5)
mTORC1 nutrient sensing Functions as part of the lysosomal signaling platform that couples amino acid availability to mTORC1 activation Beyond proton pumping, V-ATPase acts as a scaffold at lysosomal membranes for amino-acid-dependent signaling to mTORC1 via associated regulators; lysosomal acidification and membrane-localized complex assembly are linked to signaling competence (wang2020structuresofa pages 1-3, song2020theemergingroles pages 1-2, eaton2021theh+atpase(vatpase) pages 1-5) Regulation of cell growth, anabolic metabolism, nutrient sensing, and adaptation to starvation/refeeding states (wang2020structuresofa pages 1-3, eaton2021theh+atpase(vatpase) pages 1-5)
Endocytic pathway Drives progressive acidification of endosomes and late endosomes; ATP6V0E1 supports this through its role in the Vo membrane sector Proton pumping lowers luminal pH along the endocytic route, enabling receptor-ligand dissociation, cargo sorting, maturation from early to late compartments, and delivery to lysosomes; V-ATPase also interfaces with Rab-dependent trafficking responses (song2020theemergingroles pages 1-2, toshima2024transportmechanismsbetween pages 1-2, chen2024thedifferentroles pages 1-2) Endosomal maturation, receptor recycling or degradation, trafficking fidelity, proteostasis, and efficient phagosome/endosome progression (toshima2024transportmechanismsbetween pages 1-2, chen2024thedifferentroles pages 1-2)
Wnt signaling Participates indirectly as an endolysosomal/signaling hub required for pathway function V-ATPase has been shown to associate with and regulate Wnt-related signaling processes, with endosomal/lysosomal acidification and V-ATPase-associated membrane complexes contributing to pathway activation and receptor processing (wang2020structuresofa pages 1-3, abbas2020structureofvatpase pages 1-2, indrawinata2023structuralandfunctional pages 1-2) Control of development, stem-cell behavior, and cell fate programs; dysregulation can contribute to disease states (wang2020structuresofa pages 1-3, abbas2020structureofvatpase pages 1-2)
Notch signaling Supports signaling through acidification-dependent endomembrane processing V-ATPase-dependent acidification of intracellular vesicles contributes to receptor trafficking and processing steps needed for Notch pathway activity (wang2020structuresofa pages 1-3, indrawinata2023structuralandfunctional pages 1-2) Regulation of cell differentiation, developmental patterning, and tissue homeostasis (wang2020structuresofa pages 1-3, indrawinata2023structuralandfunctional pages 1-2)
Neurotransmitter loading Generates the proton motive force across synaptic vesicle membranes required for vesicular transmitter uptake In neurons, V-ATPase pumps protons into synaptic vesicles; vesicular neurotransmitter transporters then use the proton electrochemical gradient to load neurotransmitters before exocytosis (abbas2020structureofvatpase pages 1-2, abbas2020structureofvatpase pages 2-4) Synaptic vesicle filling, neurotransmission efficiency, and neural circuit function (abbas2020structureofvatpase pages 1-2, abbas2020structureofvatpase pages 2-4)
pH homeostasis Principal ATP-dependent proton pump maintaining acidity of intracellular organelles and, in some cells, extracellular acidification V-ATPase transports H+ from cytosol into organelle lumens or across the plasma membrane in specialized cells; compartment-specific localization enables pH control in lysosomes, endosomes, Golgi/TGN, and certain secretory or plasma membranes (wang2020structuresofa pages 1-3, song2020theemergingroles pages 1-2, eaton2021theh+atpase(vatpase) pages 1-5, sou2024golgiphhomeostasis pages 1-3) Maintenance of organelle identity, enzyme activity, membrane trafficking, glycosylation, cytosolic buffering, and specialized acid secretion such as bone resorption or renal acid handling (wang2020structuresofa pages 1-3, eaton2021theh+atpase(vatpase) pages 1-5, sou2024golgiphhomeostasis pages 1-3)

Table: This table summarizes the major signaling and biochemical pathways supported by V-ATPase complexes containing the Vo sector, including the likely contribution of ATP6V0E1 as a structural Vo subunit. It is useful for linking ATP6V0E1 to both canonical proton-pumping functions and broader signaling roles.

3.1 Autophagy-Lysosomal Pathway

V-ATPase-mediated lysosomal acidification is absolutely required for autophagic flux (song2020theemergingroles pages 1-2, eaton2021theh+atpase(vatpase) pages 1-5). Acidification activates lysosomal hydrolases and supports the fusion of autophagosomes with lysosomes (song2020theemergingroles pages 1-2). Dysfunction of V-ATPase activity, whether through pharmacological inhibition (e.g., with bafilomycin or concanamycin) or genetic disruption, causes accumulation of autophagosomes and impairs degradation of autophagic cargo (song2020theemergingroles pages 1-2, eaton2021theh+atpase(vatpase) pages 1-5). This is particularly relevant in neurodegenerative diseases, where impaired lysosomal acidification contributes to the accumulation of protein aggregates in conditions such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis (song2020theemergingroles pages 1-2).

3.2 mTORC1 Nutrient Sensing

The V-ATPase functions as a critical component of the lysosomal nutrient-sensing machinery that regulates mTORC1, a master regulator of cell growth and metabolism (wang2020structuresofa pages 1-3, song2020theemergingroles pages 1-2, eaton2021theh+atpase(vatpase) pages 1-5). Beyond its proton-pumping activity, the V-ATPase serves as a scaffold for amino acid-dependent activation of mTORC1 on the lysosomal surface through interactions with the Ragulator complex and Rag GTPases (wang2020structuresofa pages 1-3, eaton2021theh+atpase(vatpase) pages 1-5). This non-canonical signaling function highlights the V-ATPase as a central hub integrating metabolic information with cell growth signals (eaton2021theh+atpase(vatpase) pages 1-5).

3.3 Endocytic Trafficking and Receptor Recycling

Progressive endosomal acidification by V-ATPase enables receptor-ligand dissociation, facilitates cargo sorting, and regulates the transition between endosomal compartments (song2020theemergingroles pages 1-2, toshima2024transportmechanismsbetween pages 1-2, chen2024thedifferentroles pages 1-2). Studies have shown that V-ATPase activity influences Rab7 activation and late endosomal trafficking, with pH neutralization leading to hyper-activation of Rab7 and disruption of tubulation and mannose-6-phosphate receptor recycling on late endosomes (toshima2024transportmechanismsbetween pages 1-2). This demonstrates the intricate coupling between V-ATPase-mediated pH control and membrane trafficking machinery.

3.4 Developmental Signaling Pathways

V-ATPase activity has been implicated in Wnt and Notch signaling pathways, which are critical for development, stem cell maintenance, and tissue homeostasis (wang2020structuresofa pages 1-3, abbas2020structureofvatpase pages 1-2, indrawinata2023structuralandfunctional pages 1-2). Endosomal acidification by V-ATPase is required for proper receptor processing and signaling in both pathways (wang2020structuresofa pages 1-3, indrawinata2023structuralandfunctional pages 1-2). Additionally, ATP6AP2 (prorenin receptor), another component of the Vo complex, has been shown to participate in Wnt signaling independent of its role in V-ATPase assembly (abbas2020structureofvatpase pages 1-2).

4. Biological Processes and Disease Associations

4.1 Neurodegenerative Diseases

Impaired V-ATPase function and consequent lysosomal dysfunction are increasingly recognized as central features of multiple neurodegenerative diseases (song2020theemergingroles pages 1-2). Inadequate lysosomal acidification impairs the degradation of protein aggregates characteristic of Alzheimer's disease (amyloid-β and tau), Parkinson's disease (α-synuclein), and amyotrophic lateral sclerosis (TDP-43 and other proteins) (song2020theemergingroles pages 1-2). The emerging role of V-ATPases in neurodegenerative diseases has made them attractive therapeutic targets for enhancing lysosomal function (song2020theemergingroles pages 1-2).

4.2 Developmental and Epileptic Encephalopathies

Mutations in V-ATPase subunits, particularly the a1 subunit encoded by ATP6V0A1, cause severe neurodevelopmental disorders including developmental and epileptic encephalopathies (DEE) and progressive myoclonus epilepsy (PME) (indrawinata2023structuralandfunctional pages 1-2). These mutations impair lysosomal acidification and autophagic function, leading to neuronal cell death (indrawinata2023structuralandfunctional pages 1-2). While specific disease-causing mutations in ATP6V0E1 have not been prominently reported, the essential nature of the V-ATPase complex suggests that disruption of subunit e1 would similarly impair enzyme function.

4.3 Cancer

Many cancer cells upregulate V-ATPase expression and relocate V-ATPases to the plasma membrane, where they acidify the extracellular tumor microenvironment (eaton2021theh+atpase(vatpase) pages 1-5). This acidification promotes tumor invasion, metastasis, and evasion of immune surveillance (eaton2021theh+atpase(vatpase) pages 1-5). Additionally, cancer cells often exhibit increased dependence on autophagy for survival, making V-ATPase activity crucial for tumor cell metabolism and growth (eaton2021theh+atpase(vatpase) pages 1-5). Consequently, V-ATPase inhibition has been proposed as a potential therapeutic strategy in cancer treatment (eaton2021theh+atpase(vatpase) pages 1-5).

4.4 Other Disease Associations

V-ATPase dysfunction is associated with various other diseases depending on the affected subunit isoform and tissue distribution. Mutations in the a3 subunit cause osteopetrosis due to impaired osteoclast-mediated bone resorption (abbas2020structureofvatpase pages 1-2, eaton2021theh+atpase(vatpase) pages 1-5), while a4 subunit mutations lead to distal renal tubular acidosis due to defective acid secretion in kidney intercalated cells (eaton2021theh+atpase(vatpase) pages 1-5). Mutations in ATP6AP1 cause immunodeficiency with hepatopathy and cognitive impairment, demonstrating the complex's broad physiological importance (wang2020structuresofa pages 7-9).

5. Assembly and Regulation

5.1 Vo Complex Assembly

The assembly of the Vo complex occurs in the endoplasmic reticulum (ER) and requires specialized assembly factors including Vma12p, Vma21p, and Vma22p in yeast (homologous to TMEM199, VMA21, and CCDC115 in mammals) (wang2023structuralbasisof pages 1-2, wang2023structuralbasisof pages 2-3). These factors facilitate the stepwise assembly of Vo subunits around the c-ring and prevent premature binding of the V1 complex to incomplete Vo assemblies, thereby ensuring that proton pumping does not acidify the ER (wang2023structuralbasisof pages 1-2, wang2023structuralbasisof pages 2-3).

Structural studies show that the assembly factor complex Vma12-22p binds partially assembled Vo lacking subunits a, e, and f, and recruits these subunits to the c-ring while blocking V1 binding (wang2023structuralbasisof pages 1-2, wang2023structuralbasisof pages 2-3). Subunit e1, as a late-assembling component, is incorporated along with subunit a during this maturation process (wang2023structuralbasisof pages 1-2).

5.2 Reversible Disassembly

V-ATPases undergo reversible dissociation into V1 and Vo subcomplexes as a regulatory mechanism in response to glucose deprivation and other stress conditions in yeast and potentially in mammalian cells (eaton2021theh+atpase(vatpase) pages 1-5, klossel2024yeasttldcdomain pages 1-2). During disassembly, V1 detaches from Vo, causing both subcomplexes to adopt inactive conformations (klossel2024yeasttldcdomain pages 1-2). The RAVE complex (regulator of ATPase of vacuoles and endosomes) facilitates reassembly when conditions improve (wang2023structuralbasisof pages 1-2). Recent work has identified TLDc domain-containing proteins, such as Oxr1p in yeast, as regulators that promote V-ATPase disassembly, counteracting RAVE activity (klossel2024yeasttldcdomain pages 1-2).

6. Experimental Evidence and Technical Insights

6.1 Structural Biology

High-resolution structural determination of V-ATPases has been achieved through advances in cryo-electron microscopy (cryo-EM). The structure of human V-ATPase at 2.9-3.1 Å resolution revealed the detailed architecture of both V1 and Vo domains, enabling construction of atomic models for nearly all subunits (wang2020structuresofa pages 1-3, wang2020structuresofa pages 3-5). These structures captured V-ATPase in three different rotational states corresponding to steps in the catalytic cycle, providing insights into the mechanism of ATP-driven proton translocation (wang2020structuresofa pages 1-3, wang2020structuresofa pages 3-5).

Mass spectrometry analysis confirmed the subunit composition of purified V-ATPases and identified post-translational modifications, including the N-glycosylation sites on subunits e, a, and ATP6AP1 (wang2020structuresofa pages 3-5, wang2020structuresofa pages 7-9). Native mass spectrometry demonstrated that the V1 region has a mass consistent with A3B23C1DE13FG23 stoichiometry in SidK-bound preparations from rat brain (abbas2020structureofvatpase pages 1-2).

6.2 Functional Studies

Functional characterization of V-ATPase has been facilitated by pharmacological inhibitors such as bafilomycin and concanamycin, which specifically block Vo-mediated proton translocation (song2020theemergingroles pages 1-2, eaton2021theh+atpase(vatpase) pages 1-5). Genetic approaches, including knockout and knockdown studies of individual subunits, have elucidated subunit-specific functions. For example, studies in zebrafish and mouse models have distinguished the roles of different a-subunit isoforms in endosomal maturation versus lysosomal function (chen2024thedifferentroles pages 1-2).

Cross-linking mass spectrometry on isolated yeast vacuoles has identified novel protein-protein interactions involving V-ATPase subunits, including interactions with regulatory proteins like Rtc5 and Oxr1 (klossel2024yeasttldcdomain pages 1-2). These approaches continue to reveal new aspects of V-ATPase regulation and integration with cellular signaling networks.

7. Current Research Directions and Future Perspectives

Recent research has expanded our understanding of V-ATPase beyond its role as a simple proton pump to appreciate its functions as a signaling hub and regulatory nexus (eaton2021theh+atpase(vatpase) pages 1-5). Key areas of active investigation include:

  1. Isoform-specific functions: Understanding how different subunit isoforms, including e1 versus e2, confer compartment-specific properties and regulatory mechanisms (eaton2021theh+atpase(vatpase) pages 1-5, chen2024thedifferentroles pages 1-2).

  2. Non-canonical signaling roles: Elucidating the mechanisms by which V-ATPase scaffolds signaling complexes and participates in pathways beyond acidification (wang2020structuresofa pages 1-3, eaton2021theh+atpase(vatpase) pages 1-5).

  3. Therapeutic targeting: Developing strategies to modulate V-ATPase activity for therapeutic benefit in cancer, neurodegenerative diseases, and other conditions (song2020theemergingroles pages 1-2, eaton2021theh+atpase(vatpase) pages 1-5).

  4. Assembly and quality control: Understanding the mechanisms that ensure proper V-ATPase assembly and prevent premature or aberrant complex formation (wang2023structuralbasisof pages 1-2, wang2023structuralbasisof pages 2-3, klossel2024yeasttldcdomain pages 1-2).

  5. Lipid interactions: Characterizing how phosphatidylinositol phosphates and other lipids regulate V-ATPase localization, assembly, and activity (eaton2021theh+atpase(vatpase) pages 1-5).

Conclusion

ATP6V0E1 encodes a structurally important subunit of the V-ATPase Vo domain that contributes to the proton-translocating machinery essential for acidifying intracellular organelles. As a component of one of the most fundamental and highly conserved enzyme complexes in eukaryotic cells, subunit e1 plays an indirect but critical role in numerous cellular processes including autophagy, endocytic trafficking, protein glycosylation, neurotransmitter loading, and cellular signaling. The V-ATPase's involvement in multiple disease states, from neurodegeneration to cancer, underscores the importance of continued research into this complex and its individual subunits. Understanding the specific contributions of ATP6V0E1 to V-ATPase function, regulation, and pathology will provide insights into fundamental cell biology and may reveal new therapeutic opportunities.


References Summary

This report draws on recent high-resolution structural studies of mammalian V-ATPases (Wang et al. 2020, Abbas et al. 2020), assembly mechanism investigations (Wang et al. 2023), comprehensive reviews of V-ATPase function in health and disease (Eaton et al. 2021, Song et al. 2020, Chen et al. 2022), compartment-specific studies (Seidel 2022, Chen et al. 2024), regulatory mechanism research (Klössel et al. 2024), and pH homeostasis investigations (Sou et al. 2024, Kopp et al. 2024), primarily from the 2020-2024 literature.

References

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