Protein: Vacuolar transporter chaperone complex subunit 1 (SPX-dependent polyphosphate polymerase VTC subunit 1) (Vacuolar membrane polyphosphate polymerase accessory subunit 1) (PolyP polymerase) (Q57UM0)
Organism: Trypanosoma brucei brucei (strain 927/4 GUTat10.1)
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. VTC1 contributes only 3 transmembrane domains to the complex. The VTC complex also plays a role in vacuolar membrane fusion.
Subcellular location: Acidocalcisome membrane {ECO:0000269|PubMed:17635107}; Multi-pass membrane protein {ECO:0000255}.
Sequence: MASVIEKGLASICCVTTSSKPWAEGEADGDVKYEDLRGPGGRNTSGSVSDKRICVPQKIDPKTFFANERTFLKWMSISVMIGMMSLTLLNFGDTSSNASELAGLVLLPVSILFMIHSLFVFKDRANKIYMREPMRYDDTKGPTILVLVLGVSLGIAAIFSVQKQYYRTASSSFNDGPRFS
InterPro domains: - IPR051572: Vacuolar Transporter Chaperone Complex Subunit (family) [39-163]
- IPR003807: Domain of unknown function DUF202 (domain) [62-125]
Interaction partners: - Short-chain dehydrogenase, putative
- Putative enoyl-CoA reductase
Gene Ontology annotations:
Molecular Function (MF): GO:0003674 (molecular function), GO:0005488 (binding), GO:0003824 (catalytic activity), GO:0005515 (protein binding), GO:0016740 (transferase activity), GO:0016772 (transferase activity, transferring phosphorus-containing groups), GO:0016776 (phosphotransferase activity, phosphate group as acceptor), GO:0016301 (kinase activity), GO:0019205 (nucleobase-containing compound kinase activity), GO:0050145 (nucleoside monophosphate kinase activity), GO:0004017 (adenylate kinase activity)
Biological Process (BP): GO:0008150 (biological process), GO:0008152 (metabolic process), GO:0009987 (cellular process), GO:0051179 (localization), GO:0051234 (establishment of localization), GO:0051641 (cellular localization), GO:0071840 (cellular component organization or biogenesis), GO:0009058 (biosynthetic process), GO:0044237 (cellular metabolic process), GO:0061919 (process utilizing autophagic mechanism), GO:0071704 (organic substance metabolic process), GO:0009056 (catabolic process), GO:0051649 (establishment of localization in cell), GO:0016043 (cellular component organization), GO:0044249 (cellular biosynthetic process), GO:0044085 (cellular component biogenesis), GO:0046907 (intracellular transport), GO:0044248 (cellular catabolic process), GO:0006810 (transport), GO:0006914 (autophagy), GO:0016236 (macroautophagy), GO:0046903 (secretion), GO:0043933 (protein-containing complex organization), GO:0007034 (vacuolar transport), GO:0006996 (organelle organization), GO:0022607 (cellular component assembly), GO:0065003 (protein-containing complex assembly), GO:0007041 (lysosomal transport), GO:0007033 (vacuole organization), GO:0051259 (protein complex oligomerization), GO:0051260 (protein homooligomerization)
Cellular Component (CC): GO:0005575 (cellular component), GO:0110165 (cellular anatomical entity), GO:0005622 (intracellular anatomical structure), GO:0043226 (organelle), GO:0031975 (envelope), GO:0016020 (membrane), GO:0005737 (cytoplasm), GO:0012505 (endomembrane system), GO:0031090 (organelle membrane), GO:0031967 (organelle envelope), GO:0005739 (mitochondrion), GO:0005783 (endoplasmic reticulum), GO:0043229 (intracellular organelle), GO:0019867 (outer membrane), GO:0043227 (membrane-bounded organelle), GO:0005740 (mitochondrial envelope), GO:0031968 (organelle outer membrane), GO:0043231 (intracellular membrane-bounded organelle), GO:0098588 (bounding membrane of organelle), GO:0031966 (mitochondrial membrane), GO:0005741 (mitochondrial outer membrane)