pyk1 (SPAC4H3.10c) encodes the sole pyruvate kinase of Schizosaccharomyces pombe (EC 2.7.1.40), a cytosolic Mg2+/K+-dependent enzyme that transfers the phosphoryl group of phosphoenolpyruvate to ADP, yielding pyruvate and ATP in the final, essentially irreversible step of glycolysis. The recombinant enzyme shows sigmoidal kinetics towards phosphoenolpyruvate that become hyperbolic in the presence of fructose-1,6-bisphosphate, i.e. it is feed-forward activated like budding-yeast Cdc19, and it behaves as a dimer-tetramer equilibrium in solution. It is a soluble cytosolic protein, used as a marker of bulk cytosol (including as a bulk autophagy cargo).
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000287 magnesium ion binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: InterPro2GO (pyruvate kinase domain IPR001697/IPR015793) assigns magnesium ion binding. Pyruvate kinases require Mg2+ (with the nucleotide and at the active site) and UniProt records Mg2+ as a cofactor for pyk1; correct, but a cofactor-binding property rather than the enzyme's function. Reason: Genuine cofactor requirement; non-core. Supporting Evidence: file:SCHPO/pyk1/pyk1-uniprot.txt Name=Mg(2+); Xref=ChEBI:CHEBI:18420; |
| GO:0004743 pyruvate kinase activity | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PANTHER node PTN000212670 (PTHR11817), seeded by experimentally characterized pyruvate kinases including human PKM/PKLR, E. coli PykF/PykA, S. cerevisiae CDC19/PYK2 and pyk1 itself. pyk1 is the only pyruvate kinase-family protein in S. pombe and the node placement is sound. Supporting Evidence: file:SCHPO/pyk1/pyk1-uniprot.txt SIMILARITY: Belongs to the pyruvate kinase family. {ECO:0000305}. PMID:9790887 The purified enzyme showed sigmoidal kinetics with respect to PEP; |
| GO:0004743 pyruvate kinase activity | IDA PMID:9790887 Purification and characterization of pyruvate kinase from Sc... | ACCEPT | Summary: Nairn et al. 1998 expressed S. pombe pyruvate kinase in S. cerevisiae, purified it and characterised its kinetics towards PEP and ADP and its activation by FBP: direct assay of pyruvate kinase activity for pyk1. Supporting Evidence: PMID:9790887 Recombinant S. pombe pyruvate PMID:9790887 The purified enzyme showed sigmoidal kinetics with respect to PEP; PMID:9790887 in the presence of FBP, the kinetics were restored to Michaelis-Menten behavior. |
| GO:0004743 pyruvate kinase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Combined IEA (InterPro PK domains, RHEA:18157, EC 2.7.1.40) for pyruvate kinase activity; agrees with the IDA and IBA rows and with the UniProt catalytic-activity record. Supporting Evidence: file:SCHPO/pyk1/pyk1-uniprot.txt Reaction=pyruvate + ATP = phosphoenolpyruvate + ADP + H(+); |
| GO:0005737 cytoplasm | IBA GO_REF:0000033 | ACCEPT | Summary: IBA is_active_in cytoplasm from the pyruvate kinase node. Correct for pyk1 (cytosolic glycolytic enzyme); cytosol (EXP/HDA rows) is the more precise term. Supporting Evidence: PMID:37939137 We used the cytosolic protein Pyk1, a bulk autophagy cargo, to verify whether a protein enclosed within the autophagosome is resistant to AID-mediated degradation |
| GO:0005829 cytosol | EXP PMID:37939137 The ortholog of human REEP1-4 is required for autophagosomal... | ACCEPT | Summary: Zhao et al. 2023 (REEP/Yep1 ER-phagy paper) used endogenously tagged Pyk1-AID-mECitrine explicitly as a cytosolic bulk-autophagy cargo; supports cytosolic localisation. Supporting Evidence: PMID:37939137 We used the cytosolic protein Pyk1, a bulk autophagy cargo, to verify whether a protein enclosed within the autophagosome is resistant to AID-mediated degradation |
| GO:0005829 cytosol | HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ... | ACCEPT | Summary: Matsuyama et al. 2006 ORFeome-wide YFP localisation placed pyk1 in the cytosol; consistent with the single-protein EXP data and with its glycolytic role. Supporting Evidence: PMID:16823372 Next, we determined the localization of 4,431 proteins, corresponding to |
| GO:0006096 glycolysis | IBA GO_REF:0000033 | ACCEPT | Summary: IBA involved_in glycolysis from PTN000212670. Pyruvate kinase catalyses the final, ATP-generating step of glycolysis; pyk1 performs this step in S. pombe. Supporting Evidence: file:SCHPO/pyk1/pyk1-uniprot.txt PATHWAY: Carbohydrate degradation; glycolysis; pyruvate from D- file:SCHPO/pyk1/pyk1-uniprot.txt Reaction=pyruvate + ATP = phosphoenolpyruvate + ADP + H(+); |
| GO:0006096 glycolysis | IEA GO_REF:0000120 | ACCEPT | Summary: IEA (InterPro + UniPathway UPA00109) glycolysis; correct for the pyruvate kinase step. Supporting Evidence: file:SCHPO/pyk1/pyk1-uniprot.txt PATHWAY: Carbohydrate degradation; glycolysis; pyruvate from D- |
| GO:0030955 potassium ion binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: InterPro2GO potassium ion binding. Pyruvate kinases are K+-activated and UniProt lists K+ as a pyk1 cofactor; correct cofactor-binding statement, not the core activity. Reason: Genuine cofactor requirement; non-core. Supporting Evidence: file:SCHPO/pyk1/pyk1-uniprot.txt Name=K(+); Xref=ChEBI:CHEBI:29103; |
| GO:0061621 obsolete canonical glycolysis | IDA PMID:9790887 Purification and characterization of pyruvate kinase from Sc... | MODIFY | Summary: PomBase IDA (Nairn et al. 1998) to 'canonical glycolysis' (GO:0061621), which is now obsolete in GO. The biology is right: the enzyme catalyses the last step of glycolysis and is feed-forward activated by FBP, a glycolytic intermediate. The replacement is the parent glycolytic process term. Reason: GO:0061621 is obsolete; GO:0006096 glycolytic process is the current term for the same process. Proposed replacements: glycolytic process Supporting Evidence: PMID:9790887 The purified enzyme showed sigmoidal kinetics with respect to PEP; PMID:9790887 in the presence of FBP, the kinetics were restored to Michaelis-Menten behavior. |
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