BCAT2 is a pyridoxal 5'-phosphate-dependent branched-chain amino acid aminotransferase (EC 2.6.1.42). It reversibly transfers the amino group of leucine, isoleucine or valine to 2-oxoglutarate, producing glutamate and alpha-ketoisocaproate, alpha-keto-beta-methylvalerate or alpha-ketoisovalerate, respectively. The mitochondrial homodimer initiates BCAA catabolism upstream of the branched-chain ketoacid dehydrogenase complex; the reverse reaction regenerates amino acids from existing ketoacid skeletons. PLP binds at the active site, and a nearby CXXC motif influences substrate positioning. BCAT2 is broadly expressed, with high abundance in muscle. A shorter splice product, PP18b, occurs in the cytosolic fraction of human placenta and is distinct from the paralog BCAT1. Biallelic loss of BCAT2 activity causes hypervalinemia and hyperleucine-isoleucinemia.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005739 mitochondrion | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic annotation places BCAT2 activity in mitochondria. Reason: The canonical product has a cleaved mitochondrial presequence and a mitochondrial catalytic role. The IBA is consistent with the target evidence; O15382 in WITH/FROM is legitimate descendant evidence, not circularity. The shorter PP18b splice product prevents interpreting this gene-level assertion as universal localization of every product. The PAINT ancestral-node reconstruction was not independently replayed. Supporting Evidence: PMID:11170829 mitochondrial (only PP18a) and cytosolic (only PP18b) fractions of term placenta |
| GO:0006550 L-isoleucine catabolic process | IBA GO_REF:0000033 | ACCEPT | Summary: BCAT2 contributes the transamination step of L-isoleucine catabolism. Reason: UniProt O15382 records the isoleucine/2-oxoglutarate reaction (RHEA:24801); the human Reactome reaction independently includes that substrate. BCAT2 executes this reversible transamination upstream of BCKDH. This agrees with the existing inference; no new experimental assay or ancestral-node reconstruction is claimed. Supporting Evidence: file:human/BCAT2/BCAT2-uniprot.txt Reaction=L-isoleucine + 2-oxoglutarate = (S)-3-methyl-2-oxopentanoate + Reactome:R-HSA-70724 |
| GO:0006574 L-valine catabolic process | IBA GO_REF:0000033 | ACCEPT | Summary: BCAT2 contributes the transamination step of L-valine catabolism. Reason: UniProt O15382 records the valine/2-oxoglutarate reaction (RHEA:24813); the human Reactome reaction independently includes that substrate. BCAT2 executes this reversible transamination upstream of BCKDH. This agrees with the existing inference; no new experimental assay or ancestral-node reconstruction is claimed. Supporting Evidence: file:human/BCAT2/BCAT2-uniprot.txt Reactome:R-HSA-70724 |
| GO:0052654 L-leucine:2-oxoglutarate transaminase activity | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic inference supports the leucine-specific transaminase activity. Reason: UniProt O15382 records the leucine/2-oxoglutarate reaction (RHEA:18321); the human Reactome reaction independently includes that substrate. BCAT2 executes this reversible transamination upstream of BCKDH. This agrees with the existing inference; no new experimental assay or ancestral-node reconstruction is claimed. Supporting Evidence: file:human/BCAT2/BCAT2-uniprot.txt Reactome:R-HSA-70724 |
| GO:0052655 L-valine:2-oxoglutarate transaminase activity | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic inference supports the valine-specific transaminase activity. Reason: UniProt O15382 records the valine/2-oxoglutarate reaction (RHEA:24813); the human Reactome reaction independently includes that substrate. BCAT2 executes this reversible transamination upstream of BCKDH. This agrees with the existing inference; no new experimental assay or ancestral-node reconstruction is claimed. Supporting Evidence: file:human/BCAT2/BCAT2-uniprot.txt Reactome:R-HSA-70724 |
| GO:0052656 L-isoleucine:2-oxoglutarate transaminase activity | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic inference supports the isoleucine-specific transaminase activity. Reason: UniProt O15382 records the isoleucine/2-oxoglutarate reaction (RHEA:24801); the human Reactome reaction independently includes that substrate. BCAT2 executes this reversible transamination upstream of BCKDH. This agrees with the existing inference; no new experimental assay or ancestral-node reconstruction is claimed. Supporting Evidence: file:human/BCAT2/BCAT2-uniprot.txt Reactome:R-HSA-70724 |
| GO:0003824 catalytic activity | IEA GO_REF:0000002 | MODIFY | Summary: Refine the broad InterPro catalytic assertion to the established branched-chain aminotransferase activity. Reason: GO:0003824 is correct but uninformative at this level. GO:0004084 states the demonstrated reaction class. This MODIFY refines an existing source assertion under the supplied ActionEnum; the same activity already has stronger IDA/TAS annotations, so it is not a claim of new functional coverage or an independent experiment. Proposed replacements: branched-chain-amino-acid:2-oxoglutarate transaminase activity |
| GO:0004084 branched-chain-amino-acid:2-oxoglutarate transaminase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Combined electronic evidence assigns the core branched-chain aminotransferase activity. Reason: The EC-level function is consistent with human BCATm kinetic and structural evidence and the curated reactions in UniProt and Reactome. The mixed evidence sources need not each be treated as an independent experiment. |
| GO:0005739 mitochondrion | IEA GO_REF:0000120 | ACCEPT | Summary: Electronic localization supports mitochondria for the canonical BCAT2 product. Reason: Mouse orthology and the UniProt localization mapping agree with the canonical mitochondrial presequence and human placental fractionation evidence. This does not exclude a cytosolic shorter splice product and does not assign isoform specificity to an unscoped GOA row. Supporting Evidence: |
| GO:0009081 branched-chain amino acid metabolic process | IEA GO_REF:0000002 | MODIFY | Summary: Branched-chain amino-acid metabolism is correct for BCAT2 but less specific than its supported catabolic role. Reason: BCAT2 directly interconverts branched-chain amino acids and their keto acids, so the metabolic assertion is true. It is, however, the parent of the specific process the evidence supports and the gene already carries: GO:0009083 branched-chain amino acid catabolic process (IDA, IBA for the Ile/Val children, Reactome forward reaction), in which BCAT2 performs the first transamination upstream of BCKDH. Under the refinement rule the general term is therefore replaced by GO:0009083 rather than accepted. The reverse (reamination) direction is separately covered by the non-core GO:0009082 rows. Proposed replacements: branched-chain amino acid catabolic process Supporting Evidence: Reactome:R-HSA-508179 Reactome:R-HSA-70724 |
| GO:0009082 branched-chain amino acid biosynthetic process | IEA GO_REF:0000117 | KEEP AS NON CORE | Summary: The biosynthetic-process inference can be retained for regeneration of BCAAs from their keto acids. Reason: GO:0009082 covers formation of branched-chain amino acids and does not require de novo formation of their carbon skeletons. Reactome explicitly assigns the reverse reamination reaction to human BCAT2. Dietary BCAA essentiality therefore does not contradict this annotation. Net flux is context dependent; no human BCAT2-specific tissue-flux assay was inspected here, so this remains a contextual non-core process. Supporting Evidence: Reactome:R-HSA-508179 |
| GO:0009083 branched-chain amino acid catabolic process | IEA GO_REF:0000117 | ACCEPT | Summary: BCAT2 catalyzes an initial reaction in branched-chain amino-acid catabolism. Reason: The enzyme directly transaminates the BCAAs before downstream BCKDH chemistry. This is a core metabolic contribution even though the BCAT reaction itself is reversible; it should not be called the committed or exclusively catabolic step. |
| GO:0052654 L-leucine:2-oxoglutarate transaminase activity | IEA GO_REF:0000116 | ACCEPT | Summary: Rhea mapping supports the leucine-specific BCAT2 reaction. Reason: UniProt O15382 records the leucine/2-oxoglutarate reaction (RHEA:18321); the human Reactome reaction independently includes that substrate. BCAT2 executes this reversible transamination upstream of BCKDH. This agrees with the existing inference; no new experimental assay or ancestral-node reconstruction is claimed. Supporting Evidence: file:human/BCAT2/BCAT2-uniprot.txt Reactome:R-HSA-70724 |
| GO:0052655 L-valine:2-oxoglutarate transaminase activity | IEA GO_REF:0000116 | ACCEPT | Summary: Rhea mapping supports the valine-specific BCAT2 reaction. Reason: UniProt O15382 records the valine/2-oxoglutarate reaction (RHEA:24813); the human Reactome reaction independently includes that substrate. BCAT2 executes this reversible transamination upstream of BCKDH. This agrees with the existing inference; no new experimental assay or ancestral-node reconstruction is claimed. Supporting Evidence: file:human/BCAT2/BCAT2-uniprot.txt Reactome:R-HSA-70724 |
| GO:0052656 L-isoleucine:2-oxoglutarate transaminase activity | IEA GO_REF:0000116 | ACCEPT | Summary: Rhea mapping supports the isoleucine-specific BCAT2 reaction. Reason: UniProt O15382 records the isoleucine/2-oxoglutarate reaction (RHEA:24801); the human Reactome reaction independently includes that substrate. BCAT2 executes this reversible transamination upstream of BCKDH. This agrees with the existing inference; no new experimental assay or ancestral-node reconstruction is claimed. Supporting Evidence: file:human/BCAT2/BCAT2-uniprot.txt Reactome:R-HSA-70724 |
| GO:0005515 protein binding | IPI PMID:28514442 Architecture of the human interactome defines protein commun... | REMOVE | Summary: High-throughput interaction of BCAT2 with HSPD1 (P10809) reported in PMID:28514442. Reason: Bare GO:0005515 protein binding is uninformative about BCAT2 function and is removed under the repository protein-binding policy; removal does not mean the reported HSPD1 co-purification is false. This is a proteome-scale interaction screen and no informative molecular function of BCAT2 (for example a regulatory or adaptor activity toward HSPD1) is established by it, so no MODIFY replacement is justified. An association with the mitochondrial chaperonin HSPD1 is consistent with BCAT2 being an imported matrix client protein, a role that belongs to HSPD1 rather than BCAT2. Supporting Evidence: |
| GO:0005515 protein binding | IPI PMID:29568061 An AP-MS- and BioID-compatible MAC-tag enables comprehensive... | REMOVE | Summary: High-throughput interaction of BCAT2 with HSPD1 (P10809) reported in PMID:29568061. Reason: Bare GO:0005515 protein binding is uninformative about BCAT2 function and is removed under the repository protein-binding policy; removal does not mean the reported HSPD1 co-purification is false. This is a proteome-scale interaction screen and no informative molecular function of BCAT2 (for example a regulatory or adaptor activity toward HSPD1) is established by it, so no MODIFY replacement is justified. An association with the mitochondrial chaperonin HSPD1 is consistent with BCAT2 being an imported matrix client protein, a role that belongs to HSPD1 rather than BCAT2. Supporting Evidence: |
| GO:0005515 protein binding | IPI PMID:33961781 Dual proteome-scale networks reveal cell-specific remodeling... | REMOVE | Summary: High-throughput interaction of BCAT2 with HSPD1 (P10809) reported in PMID:33961781. Reason: Bare GO:0005515 protein binding is uninformative about BCAT2 function and is removed under the repository protein-binding policy; removal does not mean the reported HSPD1 co-purification is false. This is a proteome-scale interaction screen and no informative molecular function of BCAT2 (for example a regulatory or adaptor activity toward HSPD1) is established by it, so no MODIFY replacement is justified. An association with the mitochondrial chaperonin HSPD1 is consistent with BCAT2 being an imported matrix client protein, a role that belongs to HSPD1 rather than BCAT2. Supporting Evidence: |
| GO:0005515 protein binding | IPI PMID:40205054 Multimodal cell maps as a foundation for structural and func... | REMOVE | Summary: High-throughput interaction of BCAT2 with HSPD1 (P10809) reported in PMID:40205054. Reason: Bare GO:0005515 protein binding is uninformative about BCAT2 function and is removed under the repository protein-binding policy; removal does not mean the reported HSPD1 co-purification is false. This is a proteome-scale interaction screen and no informative molecular function of BCAT2 (for example a regulatory or adaptor activity toward HSPD1) is established by it, so no MODIFY replacement is justified. An association with the mitochondrial chaperonin HSPD1 is consistent with BCAT2 being an imported matrix client protein, a role that belongs to HSPD1 rather than BCAT2. Supporting Evidence: |
| GO:0005759 mitochondrial matrix | IEA GO_REF:0000107 | ACCEPT | Summary: Orthology places canonical BCAT2 activity in the mitochondrial matrix. Reason: The matrix is the specific compartment of the curated BCAT2 reactions and agrees with the mitochondrial targeting sequence. Retaining this canonical-product localization does not imply the shorter PP18b splice product is mitochondrial. |
| GO:0006552 L-leucine catabolic process | IEA GO_REF:0000107 | ACCEPT | Summary: The mouse-derived process annotation assigns L-leucine catabolism. Reason: UniProt O15382 records the leucine/2-oxoglutarate reaction (RHEA:18321); the human Reactome reaction independently includes that substrate. BCAT2 executes this reversible transamination upstream of BCKDH. This agrees with the existing inference; no new experimental assay or ancestral-node reconstruction is claimed. Supporting Evidence: file:human/BCAT2/BCAT2-uniprot.txt Reactome:R-HSA-70724 |
| GO:0006574 L-valine catabolic process | IEA GO_REF:0000107 | ACCEPT | Summary: The mouse-derived process annotation assigns L-valine catabolism. Reason: UniProt O15382 records the valine/2-oxoglutarate reaction (RHEA:24813); the human Reactome reaction independently includes that substrate. BCAT2 executes this reversible transamination upstream of BCKDH. This agrees with the existing inference; no new experimental assay or ancestral-node reconstruction is claimed. Supporting Evidence: file:human/BCAT2/BCAT2-uniprot.txt Reactome:R-HSA-70724 |
| GO:0097009 energy homeostasis | IEA GO_REF:0000107 | MARK AS OVER ANNOTATED | Summary: The mouse-derived energy-homeostasis annotation describes a downstream organismal outcome of BCAA handling rather than a process BCAT2 executes. Reason: The source is an automatic orthology transfer from mouse Bcat2 (O35855, the same PANTHER subfamily SF39), not a human energy-expenditure experiment. Altered whole-body energy balance after loss of a BCAA-catabolic enzyme is a systemic consequence of changed amino-acid and ketoacid fluxes; BCAT2 itself performs the transamination, not the homeostatic control. Organismal phenotypes of this kind are not treated as process participation in this review, so the term over-states the enzyme's role. It is not REMOVEd because a physiological link is plausible and the donor mouse evidence was not read here. |
| GO:0005739 mitochondrion | IDA GO_REF:0000052 | ACCEPT | Summary: Curated immunofluorescence supports mitochondrial localization. Reason: The existing HPA-derived IDA is consistent with the canonical mitochondrial product and the separate placental fractionation evidence. The HPA images and antibody/isoform resolution were not independently inspected, so no stronger isoform-resolved conclusion is added. Supporting Evidence: |
| GO:0005739 mitochondrion | ISS GO_REF:0000024 | ACCEPT | Summary: The rat-derived localization transfer places BCAT2 in mitochondria. Reason: The source explicitly transfers localization from O35854. PMID:9165094 describes rat protein expression and targeting-sequence processing in COS-1 cells; human placental fractionation separately supports mitochondrial PP18a. The rat experiment is not relabeled as a human assay. |
| GO:0009083 branched-chain amino acid catabolic process | IDA PMID:8702755 Two yeast homologs of ECA39, a target for c-Myc regulation, ... | ACCEPT | Summary: The curator’s experimental BCAA-catabolism annotation is retained. Reason: BCAT2 directly performs BCAA transamination and this is its core catabolic role. The accessible PMID:8702755 abstract reports yeast deletions and substrate assays plus identification of human homologs; it does not allow reconstruction of every assay behind the curator’s human annotation. We defer to that experimental curation while using separate human BCATm work and the human Reactome reaction as corroboration. |
| GO:0050873 brown fat cell differentiation | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: BCAT2 is annotated upstream of a negative effect on brown-fat differentiation. Reason: The qualifier and mouse donor are preserved exactly. UniProt’s by-similarity comment and the human GO-CAM place BCAT2’s metabolic activity upstream in the EP300/PRDM16 context; they do not confer acetyltransferase activity or direct PRDM16 binding on BCAT2. This remains a contextual transferred process, not a newly verified human differentiation assay. |
| GO:0004084 branched-chain-amino-acid:2-oxoglutarate transaminase activity | IDA PMID:8702755 Two yeast homologs of ECA39, a target for c-Myc regulation, ... | ACCEPT | Summary: The curator’s experimental branched-chain aminotransferase annotation is retained. Reason: This is the established human BCAT2 molecular function. The accessible PMID:8702755 abstract foregrounds yeast experiments, which is not grounds for declaring the experimental human annotation misattributed. Independent human kinetic/structural work supports the enzyme function; the original evidence code and reference remain intact. |
| GO:1903444 negative regulation of brown fat cell differentiation | ISS GO_REF:0000024 | MARK AS OVER ANNOTATED | Summary: The mouse-derived involved_in negative regulation of brown fat cell differentiation over-states BCAT2's role, which is metabolic supply upstream of the regulatory step. Reason: Ask which entity performs the regulatory step. In the mouse work summarised by UniProt (By similarity), BCAA catabolism supplies acetyl-CoA, and EP300 uses it to acetylate and inhibit PRDM16. The curated human GO-CAM (gomodel:682fbcd000004638) makes the same assignment: GO:1903444 sits on the EP300 protein-lysine acetyltransferase activity, while BCAT2 is modelled with branched-chain aminotransferase activity in BCAA catabolism, upstream of it. BCAT2 does none of the regulatory work. Its contribution is exactly what the companion row captures with the acts_upstream_of_negative_effect qualifier on GO:0050873 brown fat cell differentiation, which is kept as non-core. Claiming direct involvement in the regulation is an indirect metabolic-supply effect presented as participation. Supporting Evidence: file:human/BCAT2/BCAT2-uniprot.txt acetyl-CoA derived from branched chain amino acid catabolism is used by EP300/p300 to acetylate and inhibit PRDM16 |
| GO:0005739 mitochondrion | HTP PMID:34800366 Quantitative high-confidence human mitochondrial proteome an... | ACCEPT | Summary: The MitoCoP source assigns BCAT2 to the mitochondrial proteome. Reason: The original MitoCoP HTP annotation places BCAT2 in the human mitochondrial proteome. The study combines complementary proteomics and curation to define that proteome; placental fractionation provides separate corroboration of mitochondrial PP18a. The BCAT2 supplementary proteomics entry and isoform resolution were not independently reconstructed, so those details remain grounded in the existing curator annotation. Supporting Evidence: PMID:34800366 high-confidence proteome (MitoCoP) of 1,134 protein-coding genes |
| GO:0052654 L-leucine:2-oxoglutarate transaminase activity | IDA PMID:8702755 Two yeast homologs of ECA39, a target for c-Myc regulation, ... | ACCEPT | Summary: The experimental leucine-specific transaminase assertion is retained. Reason: UniProt O15382 records the leucine/2-oxoglutarate reaction (RHEA:18321); the human Reactome reaction independently includes that substrate. BCAT2 executes this reversible transamination upstream of BCKDH. The original experimental reference is retained. Its accessible abstract describes yeast substrate assays and human homolog identification; the human experiment behind the curated annotation was not independently reconstructed. |
| GO:0052655 L-valine:2-oxoglutarate transaminase activity | IDA PMID:8702755 Two yeast homologs of ECA39, a target for c-Myc regulation, ... | ACCEPT | Summary: The experimental valine-specific transaminase assertion is retained. Reason: UniProt O15382 records the valine/2-oxoglutarate reaction (RHEA:24813); the human Reactome reaction independently includes that substrate. BCAT2 executes this reversible transamination upstream of BCKDH. The original experimental reference is retained. Its accessible abstract describes yeast substrate assays and human homolog identification; the human experiment behind the curated annotation was not independently reconstructed. |
| GO:0052656 L-isoleucine:2-oxoglutarate transaminase activity | IDA PMID:8702755 Two yeast homologs of ECA39, a target for c-Myc regulation, ... | ACCEPT | Summary: The experimental isoleucine-specific transaminase assertion is retained. Reason: UniProt O15382 records the isoleucine/2-oxoglutarate reaction (RHEA:24801); the human Reactome reaction independently includes that substrate. BCAT2 executes this reversible transamination upstream of BCKDH. The original experimental reference is retained. Its accessible abstract describes yeast substrate assays and human homolog identification; the human experiment behind the curated annotation was not independently reconstructed. |
| GO:0005759 mitochondrial matrix | TAS Reactome:R-HSA-508179 | ACCEPT | Summary: The reverse BCAT2 reaction is assigned to the mitochondrial matrix. Reason: The complete normal Reactome summary describes reversible BCAT2-catalyzed reamination. Its separately inspected official species, compartment and catalyst fields place the human BCAT2 dimer in the mitochondrial matrix. The localization is retained, while the reaction also shows why dietary BCAA essentiality does not exclude regeneration from existing ketoacid skeletons. Supporting Evidence: Reactome:R-HSA-508179 |
| GO:0005759 mitochondrial matrix | TAS Reactome:R-HSA-70724 | ACCEPT | Summary: The forward BCAT2 reaction is assigned to the mitochondrial matrix. Reason: The complete normal Reactome summary describes reversible BCAA-to-ketoacid transamination by BCAT2. Its separately inspected official species, compartment and catalyst fields place the human dimer in the mitochondrial matrix. This supports canonical-product localization rather than a universal claim about the shorter PP18b splice product. Supporting Evidence: Reactome:R-HSA-70724 |
| GO:0004084 branched-chain-amino-acid:2-oxoglutarate transaminase activity | TAS PMID:9165094 Cloning of the rat and human mitochondrial branched chain am... | ACCEPT | Summary: The defining cloning paper supports BCAT2’s branched-chain aminotransferase assignment. Reason: The abstract identifies rat and human mitochondrial cDNAs, but the functional expression and activity sentence concerns rat BCATm in COS-1 cells. The TAS is retained with that species boundary; the human enzyme function is independently supported by human BCATm kinetic and structural work. |
| GO:0005739 mitochondrion | TAS PMID:9165094 Cloning of the rat and human mitochondrial branched chain am... | ACCEPT | Summary: The cloning-paper TAS supports mitochondrial targeting of canonical BCAT2. Reason: Both rat and human precursors have 27-residue presequences in the abstract; processing after COS-1 expression was tested for the rat protein. Human placental fractionation separately supports mitochondrial PP18a and cytosolic PP18b, so the source is not generalized to all products. Supporting Evidence: PMID:9165094 encode mature proteins of 41.2 and 41.3 kDa with presequences of 27 amino acids |
| GO:0009082 branched-chain amino acid biosynthetic process | TAS PMID:8702755 Two yeast homologs of ECA39, a target for c-Myc regulation, ... | KEEP AS NON CORE | Summary: The older biosynthetic-process statement is retained with reamination scope. Reason: The original PMID:8702755 remains unchanged and its full text was not inspected. The prior objection based solely on human BCAA essentiality is unsound: GO:0009082 does not require de novo carbon-skeleton synthesis, and curated human BCAT2 reactions include BCAA formation from keto acids. Retain the contextual process without claiming an independently verified human in-vivo biosynthetic flux experiment. |
| GO:0005515 protein binding | IPI PMID:28514442 Architecture of the human interactome defines protein commun... | REMOVE | Summary: High-throughput interaction of BCAT2 with YBEY (P58557) reported in PMID:28514442. Reason: Bare GO:0005515 protein binding is uninformative about BCAT2 function and is removed under the repository protein-binding policy; removal does not mean the reported YBEY co-purification is false. This is a proteome-scale interaction screen and no informative molecular function of BCAT2 (for example a regulatory or adaptor activity toward YBEY) is established by it, so no MODIFY replacement is justified. No functional connection between BCAT2 and the mitochondrial ribonuclease YBEY has been described. Supporting Evidence: |
| GO:0005515 protein binding | IPI PMID:33961781 Dual proteome-scale networks reveal cell-specific remodeling... | REMOVE | Summary: High-throughput interaction of BCAT2 with YBEY (P58557) reported in PMID:33961781. Reason: Bare GO:0005515 protein binding is uninformative about BCAT2 function and is removed under the repository protein-binding policy; removal does not mean the reported YBEY co-purification is false. This is a proteome-scale interaction screen and no informative molecular function of BCAT2 (for example a regulatory or adaptor activity toward YBEY) is established by it, so no MODIFY replacement is justified. No functional connection between BCAT2 and the mitochondrial ribonuclease YBEY has been described. Supporting Evidence: |
| GO:0005515 protein binding | IPI PMID:40205054 Multimodal cell maps as a foundation for structural and func... | REMOVE | Summary: High-throughput interaction of BCAT2 with YBEY (P58557) reported in PMID:40205054. Reason: Bare GO:0005515 protein binding is uninformative about BCAT2 function and is removed under the repository protein-binding policy; removal does not mean the reported YBEY co-purification is false. This is a proteome-scale interaction screen and no informative molecular function of BCAT2 (for example a regulatory or adaptor activity toward YBEY) is established by it, so no MODIFY replacement is justified. No functional connection between BCAT2 and the mitochondrial ribonuclease YBEY has been described. Supporting Evidence: |
| GO:0030170 pyridoxal phosphate binding | IDA PMID:11264579 The structure of human mitochondrial branched-chain aminotra... | NEW | Summary: Human BCAT2 directly binds the PLP cofactor in its active site. Reason: Human BCATm crystal structures establish the PLP cofactor linked to mature Lys202 (precursor Lys229). UniProt independently records the cofactor and modified lysine. GO:0030170 is a molecular-function binding term distinct from the existing transaminase activity and is absent from the 41 source assertions. The cofactor supports the same catalytic unit; this proposal does not create a second metabolic process or claim a second independent catalytic core. Supporting Evidence: PMID:11264579 is covalently linked to the epsilon-amino group of the active-site lysine, Lys202, via a Schiff-base linkage file:human/BCAT2/BCAT2-uniprot.txt |
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Download this section (compressed HTML)Q: Under which human tissue and nutrient conditions does BCAT2 carry net reamination flux, and how much of that flux is attributable to BCAT2 rather than BCAT1?
Q: Does the shorter cytosolic PP18b splice product retain the substrate specificity, catalytic efficiency and dimer organization of the canonical mitochondrial product?
Experiment: Compare purified canonical mature BCAT2 and PP18b under matched conditions, measuring PLP occupancy, oligomeric state and kinetics in both transamination directions. Separately test subcellular distribution of the endogenous products in human cells.
Hypothesis: The large N-terminal deletion can alter catalytic or assembly properties in addition to changing subcellular targeting.
Type: isoform-resolved biochemical and localization analysis
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