P78810 · VTC4_SCHPO

Function

function

Catalytic subunit of the vacuolar transporter chaperone (VTC) complex. The VTC complex acts as a vacuolar polyphosphate polymerase that catalyzes the synthesis of inorganic polyphosphate (polyP) via transfer of phosphate from ATP to a growing polyP chain, releasing ADP. VTC exposes its catalytic domain vtc4 to the cytosol, where the growing polyP chain winds through a tunnel-shaped pocket, integrating cytoplasmic polymer synthesis with polyP membrane translocation. The VTC complex carries 9 vacuolar transmembrane domains, which are likely to constitute the translocation channel into the organelle lumen. PolyP synthesis is tightly coupled to its transport into the vacuole lumen, in order to avoid otherwise toxic intermediates in the cytosol, and it depends on the proton gradient across the membrane, formed by V-ATPase. The VTC complex also plays a role in vacuolar membrane fusion.

Catalytic activity

Cofactor

Mn2+ (UniProtKB | Rhea| CHEBI:29035 )

Activity regulation

Activity of the enzyme is Mn2+-dependent and enhanced in the presence of pyrophosphate (PPi).

Features

Showing features for binding site, active site.

TypeIDPosition(s)Description
Binding site198ATP (UniProtKB | ChEBI)
Binding site262ATP (UniProtKB | ChEBI)
Binding site264ATP (UniProtKB | ChEBI)
Binding site279ATP (UniProtKB | ChEBI)
Binding site292ATP (UniProtKB | ChEBI)
Binding site357ATP (UniProtKB | ChEBI)
Binding site359ATP (UniProtKB | ChEBI)
Binding site421Mn2+ (UniProtKB | ChEBI)
Active site453

GO annotations

AspectTerm
Cellular Componentfungal-type vacuole membrane
Cellular Componentvacuolar transporter chaperone complex
Molecular FunctionATP binding
Molecular Functionmetal ion binding
Molecular Functiontransferase activity
Biological Processenergy reserve metabolic process
Biological Processmicroautophagy
Biological Processpolyphosphate biosynthetic process
Biological Processpolyphosphate metabolic process
Biological Processvacuolar transport
Biological Processvacuole fusion, non-autophagic

Keywords

Names & Taxonomy

Protein names

  • Recommended name
    Vacuolar transporter chaperone complex subunit 4
  • Alternative names
    • Polyphosphate kinase
    • SPX-dependent polyphosphate polymerase VTC subunit 4
    • Vacuolar membrane polyphosphate polymerase catalytic subunit (PolyP polymerase) (EC:2.7.4.1
      ) . EC:2.7.4.1 (UniProtKB | ENZYME | Rhea)

Gene names

    • Name
      vtc4
    • ORF names
      SPCC1322.14c

Organism names

Accessions

  • Primary accession
    P78810
  • Secondary accessions
    • Q1L850

Proteomes

Organism-specific databases

Subcellular Location

Features

Showing features for topological domain, transmembrane.

TypeIDPosition(s)Description
Topological domain1-631Cytoplasmic
Transmembrane632-652Helical
Topological domain653-657Vacuolar
Transmembrane658-678Helical
Topological domain679-697Cytoplasmic
Transmembrane698-718Helical
Topological domain719-721Vacuolar

Keywords

PTM/Processing

Features

Showing features for chain, modified residue.

TypeIDPosition(s)Description
ChainPRO_00003633961-721Vacuolar transporter chaperone complex subunit 4
Modified residue495Phosphoserine
Modified residue497Phosphothreonine
Modified residue501Phosphoserine
Modified residue534Phosphothreonine
Modified residue546Phosphoserine

Keywords

Proteomic databases

PTM databases

Interaction

Subunit

The VTC core complex is an integral membrane heterooligomer composed of at least the catalytic subunit vtc4 and the accessory subunits vtc1 and vtc2. vtc1 is a small membrane protein without hydrophilic domain. Vtc2 and vtc4 are related and have 2 hydrophilic domains that face the cytosol, an N-terminal SPX domain and the central core domain. The central core in vtc4 is the catalytic domain.

Protein-protein interaction databases

Structure

Family & Domains

Features

Showing features for domain, compositional bias, region.

TypeIDPosition(s)Description
Domain1-146SPX
Compositional bias490-515Polar residues
Region490-547Disordered
Compositional bias526-547Polar residues

Domain

The SPX domain has very high affinity for inositol polyphosphates. SPX domains may integrate inositol pyrophosphates (PP-InsP)-dependent signaling to adapt cytosolic phosphate concentrations to different metabolic situations.

Sequence similarities

Belongs to the VTC4 family.

Keywords

Phylogenomic databases

Family and domain databases

Sequence

  • Sequence status
    Complete
  • Length
    721
  • Mass (Da)
    83,635
  • Last updated
    2000-06-01 v2
  • Checksum
    DF4471E8FC0A6BCF
MKFGQLLKETLMYEYKYSYVNYDKLKKEIKRRNDQGGWSEEDESDFVELLEKELDKVYSFQKNKSAEVMERIRFCEEQTDEVVRRLDSDNPPNENDFAILETELTDIMATVHDLAKFSELNYTAFYKIIKKHDKHTGWILKPVFAARLNAKPFFKEQYDLLVVKLSKLYDFVRTRGSPIKGDSAAGGTQQNFVRQTTKYWVHPNNVTELKIYILKHLPVLVFNPNKEFAREDAAITSIYYDNDDLDFYLGRLEKREGAEAIRLRWYGNMDNNNIFVERKTHREDWTGEKSVKARFPLKEKYVNAFLRGDYTVEEAFAKMRKDGKKSLKEIESLERLAKEVQYTVLSRGMKPYVRSFYERTAFQLPGDARVRISLDTNLSLIREDGPSRAGNNWRRMDIGIDYPFDQLPDEDIVRFPYAILEVKLQTQFGQDPPEWVNNLVNSHLVEAVPKFSKFIHGVSTLFYDRVTLLPYWFPQMDIDIRKPATHTFIQGRSQSGTHSSSVSANVLTDSENTPIHADGDNYVDEESRIGSSSTRNDNSTFQTSDSFQELDERTNLLDISKRKGRDSFVAALNSRLKDIKDSFFLETVPKFEEPTEPTVIYEQKYVSPPGKRIYVPVRVEPKTYFALERTYLDYLRYSILMGSIGITLFSFAKTRSGILGAASFTLVALFAIFYSTFLYLWRAVNIAKHNAVRYDDRFGPTAICVITFAAISANVILNFNA

Features

Showing features for compositional bias, sequence conflict.

TypeIDPosition(s)Description
Compositional bias490-515Polar residues
Compositional bias526-547Polar residues
Sequence conflict580in Ref. 2; BAA13821
Sequence conflict714in Ref. 2; BAA13821

Keywords

Sequence databases

Nucleotide SequenceProtein SequenceMolecule TypeStatus
CU329672
EMBL· GenBank· DDBJ
CAA22867.1
EMBL· GenBank· DDBJ
Genomic DNA
D89159
EMBL· GenBank· DDBJ
BAA13821.1
EMBL· GenBank· DDBJ
mRNA

Genome annotation databases

Similar Proteins

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