ATP6V1D Research Notes

Gene Identity

• UniProt: Q9Y5K8 (VATD_HUMAN)
• Gene symbol: ATP6V1D (also known as ATP6M, VATD)
• Protein: V-type proton ATPase subunit D; 247 amino acids, ~28 kDa

Core V-ATPase Biology

ATP6V1D encodes the D subunit of the V1 peripheral sector of the vacuolar-type H+-ATPase (V-ATPase). This is a ubiquitously expressed, evolutionarily conserved subunit that forms part of the central rotor of the V1 domain.

PMID:18752060

The cryo-EM structure of the complete human V-ATPase (Wang et al. 2020) places subunit D as one of two central rotor subunits (D and F) that transmit ATP hydrolysis energy from the catalytic head to the V0 ring.

PMID:33065002

Smith et al. (2008) directly demonstrated that the human D subunit physically interacts with the V0 d subunit (d1 and d2) and with subunit F, establishing that subunit D forms part of the central stalk in man:

PMID:18752060

Role in mTORC1 Amino Acid Sensing

Zoncu et al. (2011) demonstrated that the V-ATPase is required for mTORC1 activation by amino acids through an inside-out mechanism. The V1 subunit D directly contacts the Ragulator complex:

PMID:22053050

PMID:22053050

PMID:22053050

The V-ATPase acts upstream of the Rag GTPases and its ATP hydrolysis (not just the proton gradient) is required for amino acid signaling:

PMID:22053050

Subcellular Localization

• Primary: lysosomal membrane (as part of V-ATPase complex on lysosomes)
• Also documented on: Golgi, endosomes, plasma membrane (in some cell types), clathrin-coated vesicles
• Notably, ATP6V1D also localizes to centrosome and cilia base (via SNX10 interaction)

PMID:21844891
PMID:21844891

Ciliogenesis Role

ATP6V1D (with the whole V-ATPase complex) was found required for ciliogenesis in vitro. Its interaction with sorting nexin SNX10 targets V-ATPase to the centrosome.

PMID:21844891

This is a secondary function relative to the primary proton-pump/acidification role. The ciliogenesis role appears to operate through V-ATPase's vesicular trafficking/acidification function rather than being independent.

V-ATPase Structure (Human)

PMID:33065002

PMID:33065002

Regulation of Macroautophagy

V-ATPase is broadly required for lysosomal function and autophagy. The annotation to "regulation of macroautophagy" (PMID:22982048) is an indirect inference; direct evidence for a specific regulatory function of subunit D in macroautophagy control, beyond its role in lysosomal acidification, is lacking.

[PMID:22982048 - abstract only; NAS annotation from ParkinsonsUK-UCL - indirect/downstream effect of lysosomal acidification function]

Curation Notes

• The annotations to guanyl nucleotide exchange factor activator activity (GO:0160124) and positive regulation of TORC1 signaling (GO:1904263) from PMID:22053050 reflect a genuine secondary function: the V-ATPase complex (specifically V1-Ragulator interaction involving subunit D) acts upstream of Rag GTPase activation in the mTORC1 amino acid sensing pathway.
• The cytosol annotations (multiple Reactome TAS) are consistent with the fact that the V1 domain is a peripheral complex on the cytoplasmic face of membranes.
• Extracellular exosome (HDA) annotations from proteomics studies are technically valid observations but represent non-functional localization data for a structural component that may co-purify with exosome membrane fragments.
• Cilium and centrosome annotations (IDA from PMID:21844891) are supported but represent a secondary function.

Falcon deep research synthesis (2026-06-21)

Falcon deep research has now completed (file:human/ATP6V1D/ATP6V1D-deep-research-falcon.md,
21 citations). It corroborates the central-rotor core above and adds general
V-ATPase regulatory detail; no change to annotation calls.

• Core confirmed. D is one of the two central-rotor (central-stalk)
  subunits (with F); it transmits torque from A3B3 ATP hydrolysis to the V0
  proteolipid ring, coupling chemistry to proton translocation. Ubiquitous,
  essential, not catalytic. No change to the rotor/proton-transport-coupling calls.
• Reversible-assembly regulation (Sava 2024; Ratto 2022). In continuously fed
  mammalian cells, V1–V0 assembly/disassembly occurs during the lysosome
  regeneration cycle with rapid cytosolic↔membrane exchange of V1 subunits,
  distinct from amino-acid-depletion control and not requiring mTORC1 changes
  in the fed state. Relevant regulatory context for the PN regulation branch.
• Mode-switching (Kosmidis 2022). Single mammalian-brain V-ATPase stochastically
  switches between proton-pumping, inactive, and proton-leaky modes, tuned by ATP
  and the electrochemical proton gradient — affecting vesicle-acidification and
  neurotransmitter-loading dynamics. Mechanistic context, not a D-specific MF.
• Disease. No ATP6V1D-specific Mendelian disease reported; the section is
  generic V-ATPase (neurodegeneration, dRTA, osteopetrosis via a3, cancer).
  Non-core context.

Net: no change to calls — D is the ubiquitous central-rotor V1 subunit coupling
ATP hydrolysis to proton translocation.