Protein: Vacuolar transporter chaperone 3 complex subunit 3 (Phosphate metabolism protein 2) (SPX-dependent polyphosphate polymerase VTC subunit 3) (Vacuolar membrane polyphosphate polymerase accessory subunit 3) (PolyP polymerase) (Q02725)
Organism: Saccharomyces cerevisiae (strain ATCC 204508 / S288c) (Baker's yeast)
Function: Accessory subunit of the vacuolar transporter chaperone (VTC) complex. The VTC complex acts as 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. Required for SEC18/NSF activity in SNARE priming, membrane binding of LMA1 and V(0) trans-complex formation. Binds inositol hexakisphosphate (Ins6P) and similar inositol polyphosphates, such as 5-diphospho-inositol pentakisphosphate (5-InsP7); these are important intracellular signaling molecules. Inositol polyphosphate binding promotes vacuolar polyphosphate synthesis.
Subcellular location: Vacuole membrane {ECO:0000269|PubMed:12584253, ECO:0000269|PubMed:19390046}; Multi-pass membrane protein {ECO:0000269|PubMed:12584253}. Cytoplasm, cell cortex {ECO:0000269|PubMed:17079729, ECO:0000269|PubMed:19390046}. Endoplasmic reticulum membrane {ECO:0000269|PubMed:17079729}; Multi-pass membrane protein {ECO:0000269|PubMed:12584253}. Cytoplasmic vesicle, autophagosome membrane {ECO:0000269|PubMed:17079729}; Multi-pass membrane protein {ECO:0000269|PubMed:12584253}.
Sequence: MLFGIKLANDVYPPWKDSYIDYERLKKLLKESVIHDGRSSVDSWSERNESDFVEALDKELEKVYTFQISKYNAVLRKLDDLEENTKSAEKIQKINSEQFKNTLEECLDEAQRLDNFDRLNFTGFIKIVKKHDKLHPNYPSVKSLLQVRLKELPFNNSEEYSPLLYRISYLYEFLRSNYDHPNTVSKSLASTSKLSHFSNLEDASFKSYKFWVHDDNIMEVKARILRHLPALVYASVPNENDDFVDNLESDVRVQPEARLNIGSKSNSLSSDGNSNQDVEIGKSKSVIFPQSYDPTITTLYFDNDFFDLYNNRLLKISGAPTLRLRWIGKLLDKPDIFLEKRTFTENTETGNSSFEEIRLQMKAKFINNFIFKNDPSYKNYLINQLRERGTQKEELEKLSRDFDNIQNFIVEEKLQPVLRATYNRTAFQIPGDQSIRVTIDSNIMYIREDSLDKNRPIRNPENWHRDDIDSNIPNPLRFLRAGEYSKFPYSVMEIKVINQDNSQMPNYEWIKDLTNSHLVNEVPKFSLYLQGVASLFGEDDKYVNILPFWLPDLETDIRKNPQEAYEEEKKTLQKQKSIHDKLDNMRRLSKISVPDGKTTERQGQKDQNTRHVIADLEDHESSDEEGTALPKKSAVKKGKKFKTNAAFLKILAGKNISENGNDPYSDDTDSASSFQLPPGVKKPVHLLKNAGPVKVEAKVWLANERTFNRWLSVTTLLSVLTFSIYNSVQKAEFPQLADLLAYVYFFLTLFCGVWAYRTYLKRLTLIKGRSGKHLDAPVGPILVAVVLIVTLVVNFSVAFKEAARRERGLVNVSSQPSLPRTLKPIQDFIFNLVGE
InterPro domains: - IPR003807: Domain of unknown function DUF202 (domain) [698-763]
- IPR042267: VTC domain superfamily (homologous_superfamily) [204-559]
- IPR004331: SPX domain (domain) [1-145]
- IPR051572: Vacuolar Transporter Chaperone Complex Subunit (family) [1-802]
- IPR018966: VTC domain (domain) [205-536]
Interaction partners: - Vacuolar transporter chaperone complex subunit 4
- Vacuolar transporter chaperone complex subunit 1
- Inorganic phosphate transporter PHO84
- Phosphate system positive regulatory protein PHO81
- Vacuole transporter chaperone complex subunit 5
- Putative cyclin-dependent kinase inhibitor SPL2
- Glycerophosphocholine phosphodiesterase GDE1
- Vacuolar transporter chaperone complex subunit 2
- Acid phosphatase PHO11
- Acid phosphatase PHO12
Gene Ontology annotations:
Molecular Function (MF): GO:0003674 (molecular function), GO:0005488 (binding), GO:0036094 (small molecule binding), GO:0043167 (ion binding), GO:0005515 (protein binding), GO:0043168 (anion binding), GO:0043178 (alcohol binding), GO:0005516 (calmodulin binding)
Biological Process (BP): GO:0008150 (biological process), GO:0008152 (metabolic process), GO:0065007 (biological regulation), GO:0051179 (localization), GO:0050896 (response to stimulus), GO:0050789 (regulation of biological process), GO:0009987 (cellular process), GO:0023052 (signaling), GO:0051641 (cellular localization), GO:0009058 (biosynthetic process), GO:0044237 (cellular metabolic process), GO:0044281 (small molecule metabolic process), GO:0050794 (regulation of cellular process), GO:0051234 (establishment of localization), GO:0051716 (cellular response to stimulus), GO:0071840 (cellular component organization or biogenesis), GO:0061919 (process utilizing autophagic mechanism), GO:0071704 (organic substance metabolic process), GO:0033036 (macromolecule localization), GO:0009056 (catabolic process), GO:0007154 (cell communication), GO:0007165 (signal transduction), GO:0006793 (phosphorus metabolic process), GO:0046907 (intracellular transport), GO:0035556 (intracellular signal transduction), GO:0006082 (organic acid metabolic process), GO:0044248 (cellular catabolic process), GO:0006810 (transport), GO:0070727 (cellular macromolecule localization), GO:0051649 (establishment of localization in cell), GO:0016043 (cellular component organization), GO:0044249 (cellular biosynthetic process), GO:0006914 (autophagy), GO:0043436 (oxoacid metabolic process), GO:0006797 (polyphosphate metabolic process), GO:0016237 (lysosomal microautophagy), GO:0008104 (protein localization), GO:0007034 (vacuolar transport), GO:0006996 (organelle organization), GO:0019932 (second-messenger-mediated signaling), GO:0007033 (vacuole organization), GO:0048284 (organelle fusion), GO:0048016 (inositol phosphate-mediated signaling), GO:0097576 (vacuole fusion), GO:0042144 (vacuole fusion, non-autophagic)
Cellular Component (CC): GO:0005575 (cellular component), GO:0032991 (protein-containing complex), GO:0110165 (cellular anatomical entity), GO:0005622 (intracellular anatomical structure), GO:0043226 (organelle), GO:0016020 (membrane), GO:0140535 (intracellular protein-containing complex), GO:0005737 (cytoplasm), GO:0012505 (endomembrane system), GO:0101031 (chaperone complex), GO:0031090 (organelle membrane), GO:0043229 (intracellular organelle), GO:0005773 (vacuole), GO:0005783 (endoplasmic reticulum), GO:0043227 (membrane-bounded organelle), GO:0000323 (lytic vacuole), GO:0043231 (intracellular membrane-bounded organelle), GO:0098588 (bounding membrane of organelle), GO:0000322 (storage vacuole), GO:0005774 (vacuolar membrane), GO:0000324 (fungal-type vacuole), GO:0098852 (lytic vacuole membrane), GO:0000329 (fungal-type vacuole membrane)