Gene Ontology annotation through association of InterPro records with GO terms
Annotation inferences using phylogenetic trees
Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt
Combined Automated Annotation using Multiple IEA Methods
Identification of the alpha-aminoadipic semialdehyde dehydrogenase-phosphopantetheinyl transferase gene, the human ortholog of the yeast LYS5 gene.
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Human AASDHPPT functionally complemented a yeast lys5 knockout, supporting phosphopantetheinylation of alpha-aminoadipate semialdehyde dehydrogenase.
"Complementation studies in the yeast knockout demonstrate that the human homolog encodes alpha-aminoadipate dehydrogenase phosphopantetheinyl transferase activity."
Cloning, expression, and characterization of a human 4'-phosphopantetheinyl transferase with broad substrate specificity.
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The cloned human enzyme was reported as a predominantly cytosolic monomer.
"The human enzyme, which is expressed mainly in the cytosolic compartment in a wide range of tissues, is a 329-residue, monomeric protein."
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Purified human AASDHPPT transfers phosphopantetheine from CoA to the ACP domains of both cytosolic FASN and the mitochondrial ACP.
"The enzyme is capable of transferring the 4'-phosphopantetheine moiety of coenzyme A to a conserved serine residue in both the acyl carrier protein domain of the human cytosolic multifunctional fatty acid synthase and the acyl carrier protein associated independently with human mitochondria."
Towards a proteome-scale map of the human protein-protein interaction network.
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This source is a proteome-scale yeast two-hybrid screen rather than a targeted mechanistic study of AASDHPPT.
"Using a stringent, high-throughput yeast two-hybrid system, we tested pairwise interactions among the products of approximately 8,100 currently available Gateway-cloned open reading frames and detected approximately 2,800 interactions."
Mechanism and substrate recognition of human holo ACP synthase.
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Structures of human AASDHPPT with CoA/Mg2+ and with CoA/ACP directly define its donor and acceptor recognition.
"We determined the crystal structure of the human phosphopantetheinyl transferase, a eukaryotic phosphopantetheinyl transferase characterized, complexed with CoA and Mg(2+), and in ternary complex with CoA and ACP. The involvement of key residues in ligand binding and catalysis was confirmed by mutagenesis and kinetic analysis."
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Mutagenesis identifies Glu181 and Lys185 as key acid/base catalysts in the human transferase reaction.
"Besides the structural data observed in the complexes, the role of Glu181 and Lys185 as key acid/base catalysts is strongly supported by the observed significant loss of activity for the Glu181Gln, Glu181Ala, and Lys185Ala mutant proteins."
Large-scale proteomics and phosphoproteomics of urinary exosomes.
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The HDA source profiled a large human urinary-exosome proteome by LC-MS/MS.
"Here, we used LC-MS/MS to profile the proteome of human urinary exosomes. Overall, the analysis identified 1132 proteins unambiguously, including 177 that are represented on the Online Mendelian Inheritance in Man database of disease-related genes, suggesting that exosome analysis is a potential approach to discover urinary biomarkers."
Defining the human deubiquitinating enzyme interaction landscape.
Acyl carrier protein-specific 4'-phosphopantetheinyl transferase activates 10-formyltetrahydrofolate dehydrogenase.
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Human AASDHPPT converts apo-ALDH1L1/FDH to its catalytically active holoenzyme.
"In the current study, we demonstrate that the broad specificity human PPT converts apo-FDH to holoenzyme and thus activates FDH catalysis."
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Recombinant human AASDHPPT transfers phosphopantetheine specifically to FDH Ser354, restoring 10-formyltetrahydrofolate dehydrogenase activity.
"In our experiments, incubation of this enzyme with purified recombinant human PPT in the presence of CoA and Mg 2+ restored 10-fTHF dehydrogenase activity. Using a CoA-derived fluorescent reporter, we have also directly demonstrated that recombinant PPT can modify FDH in vitro . Phosphopantetheinylation by PPT occurs specifically at serine 354 of FDH because replacement of this serine with alanine prevented this covalent modification."
Enzymatic properties of ALDH1L2, a mitochondrial 10-formyltetrahydrofolate dehydrogenase.
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Recombinant AASDHPPT activates human mitochondrial ALDH1L2/mtFDH by modifying its carrier-protein serine 375.
"Despite the lack of typical ALDH catalysis, mtFDH was able to perform the characteristic 10-fTHF dehydrogenase reaction after reactivation by recombinant 4'-phosphopantetheinyl transferase (PPT) in the presence of coenzyme A. Using site-directed mutagenesis, it was determined that PPT modifies mtFDH specifically at Ser375."
A proteome-scale map of the human interactome network.
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This source is a systematic binary-interactome map rather than targeted functional characterization of AASDHPPT partners.
"Here, we describe a systematic map of ?14,000 high-quality human binary protein-protein interactions."
Architecture of the human interactome defines protein communities and disease networks.
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BioPlex 2.0 reports candidate co-associations from affinity-purification mass spectrometry, not necessarily direct binary interactions.
"With more than 56,000 candidate interactions, BioPlex 2.0 contains more than 29,000 previously unknown co-associations and provides functional insights into hundreds of poorly characterized proteins while enhancing network-based analyses of domain associations, subcellular localization, and co-complex formation."
A reference map of the human binary protein interactome.
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HuRI is a large binary-interaction map whose individual interactions generally require functional follow-up.
"Here, we present HuRI, a systematically generated human protein interactome map with more than 50,000 PPIs of high biophysical quality. While HuRI displays highly significant overlap with known functional relationships, the cellular function of most individual PPIs remains to be elucidated."
Chemical Proteomic Profiling of Protein 4'-Phosphopantetheinylation in Mammalian Cells.
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Chemical proteomics in human HepG2 cells recovered known mammalian phosphopantetheinylated proteins and mapped their modification sites.
"In combination with a quantitative chemical proteomic platform, we enriched and identified all the currently known 4'-phosphopantetheinylated proteins with high confidence, and unambiguously determined their exact sites of modification."
Dual proteome-scale networks reveal cell-specific remodeling of the human interactome.
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BioPlex 3.0 is an affinity-purification mass-spectrometry interaction map whose associations can vary between cell lines.
"Through affinity-purification mass spectrometry, we have created two proteome-scale, cell-line-specific interaction networks. The first, BioPlex 3.0, results from affinity purification of 10,128 human proteins-half the proteome-in 293T cells and includes 118,162 interactions among 14,586 proteins."
Mitochondrial phosphopantetheinylation is required for oxidative metabolism.
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In mouse C2C12 cells, Aasdhppt deficiency reduces holo- and octanoyl-NDUFAB1, directly connecting the enzyme to mitochondrial ACP modification and mtFAS.
"We found that relative to control cells, PPT-deficient cells have reduced levels of both holo- and octanoyl-NDUFAB1 (Fig. 2F and G)."
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Complementary localization assays place a subpopulation of the tested mammalian PPT in the mitochondrial matrix.
"We observed significant Venus signal only when PPT-VN cells were co-expressed with either CS-VC or NDUFAB1-VC, indicating that PPT localizes to the mitochondrial matrix (Fig. 3F–H, see Supplementary Fig. 3G for gating strategy)."
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Five substitutions corresponding to human AASDHPPT ClinVar variants of uncertain significance (R47H, A72T, W79G, R83C, and K96E) showed reduced rescue of mtFAS endpoints when modeled in the PPT-deficient C2C12 system.
"We found that all variants, except for PPT-GFP P12S, exhibited weaker rescue than wild type PPT (Fig. 5F–H, Supplementary Fig. 5G). Of note, cells expressing the PPT-GFP W79G variant showed low levels of protein expression compared to the other variants (Fig. 5F, Supplementary Fig. 5G–H) despite expression from the same promoter, suggesting that this variant may result in protein instability. These data identify R47H, A72T, W79G, R83C, and K96E as potential clinically observed pathologic variants of AASDHPPT, with molecular phenotypes attributable to altered mtFAS activity and perturbed cellular respiration."
Phosphopantetheine conjugation of the ACP domain of FAS
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Reactome represents cytosolic AASDHPPT transferring phosphopantetheine from CoA to FASN ACP Ser2156.
"Cytosolic AASDHPPT (alpha-aminoadipic semialdehyde dehydrogenase-phosphopantetheinyl transferase) catalyzes the transfer of a phosphopantetheine moiety from coenzyme A to serine 2156 within the ACP domain of FAS (fatty acyl synthase)."
Vitamin B5 (pantothenate) metabolism
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Reactome places the AASDHPPT reaction in the broad vitamin B5/CoA metabolism pathway because pantothenate supplies CoA and phosphopantetheine.
"Vitamin B5 ((R)-pantothenate, PanK), is an essential precursor for the synthesis of the metabolic cofactor Coenzyme A (CoA-SH) (Robishaw and Neely 1985) and is the prosthetic group of acyl carrier protein (ACP) (Joshi et al. 2003)."
UniProtKB/Swiss-Prot record for human AASDHPPT (Q9NRN7)
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UniProt records broad transfer of CoA-derived phosphopantetheine to serine in protein acceptors including the FASN ACP domain.
"CC -!- FUNCTION: Catalyzes the post-translational modification of target
CC proteins by phosphopantetheine. Can transfer the 4'-phosphopantetheine
CC moiety from coenzyme A, regardless of whether the CoA is presented in
CC the free thiol form or as an acetyl thioester, to a serine residue of a
CC broad range of acceptors including the acyl carrier domain of FASN."
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UniProt records cytosolic localization for the reviewed human protein.
"CC -!- SUBCELLULAR LOCATION: Cytoplasm, cytosol {ECO:0000269|PubMed:12815048}."