ALAS2 is the erythroid 5-aminolevulinate synthase, a mitochondrial pyridoxal 5'-phosphate (PLP)-dependent enzyme that catalyzes the condensation of glycine and succinyl-CoA to form 5-aminolevulinate, CoA and CO2. This first step of heme biosynthesis supplies the heme component of hemoglobin during erythropoiesis. Human ALAS2 forms a homodimer with active sites built from both subunits; PLP forms an internal aldimine with Lys391. An N-terminal targeting sequence directs mitochondrial import, and the mature enzyme acts on the matrix side of the inner membrane. The major exon-4-skipped isoform retains catalytic activity and mitochondrial targeting. ALAS2 differs from the broadly expressed ALAS1 isozyme in its erythroid specialization and iron-responsive translation. Its activity is also controlled by a C-terminal autoinhibitory extension, and hypoxia stabilizes the protein in erythroid cell experiments. Physical association with the ATP-specific succinyl-CoA synthetase beta subunit SUCLA2 is established, while the extent of substrate channeling by this interaction remains unresolved. Loss-of-function variants cause X-linked sideroblastic anemia; C-terminal gain-of-function variants cause X-linked protoporphyria.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005739 mitochondrion | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic (IBA) assertion that ALAS2 is active in the mitochondrion. This is well supported: ALAS2 has an N-terminal mitochondrial transit peptide and localizes to the matrix side of the mitochondrial inner membrane, consistent with the human mitochondrial enzyme. Reason: Correct compartment and consistent with experimental localization data for human ALAS2. A more specific term (mitochondrial matrix) is also annotated separately. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000343737 SUPPORTS TRANSFER Seeded ancestral assertion retained against the conserved human mitochondrial catalytic function. The PAINT tree/MSA was not reconstructed; donor count and target self-evidence are not treated as defects. Supporting Evidence: PMID:10727444 The first and the rate-limiting enzyme of heme biosynthesis is delta-aminolevulinate synthase (ALAS), which is localized in mitochondria file:human/ALAS2/ALAS2-uniprot.txt Localizes to the matrix side of the mitochondrion |
| GO:0006783 heme biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic (IBA) assertion that ALAS2 participates in heme biosynthesis. ALAS2 catalyzes the first and rate-limiting step of the heme biosynthetic pathway, so this is a core biological process. Reason: Directly supported by the enzyme's catalytic role at the committed entry point of the heme pathway; conserved across ALAS orthologs. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000343737 SUPPORTS TRANSFER Seeded ancestral assertion retained against the conserved human mitochondrial catalytic function. The PAINT tree/MSA was not reconstructed; donor count and target self-evidence are not treated as defects. Supporting Evidence: PMID:32499479 The first and rate-limiting step is carried out by 5β²-aminolevulinate synthase (ALAS; EC 2.3.1.37) in the mitochondria PMID:2050125 5-Aminolevulinate synthase (ALAS) catalyzes the first step of the heme biosynthetic pathway |
| GO:0003870 5-aminolevulinate synthase activity | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic (IBA) assertion of the defining molecular function of ALAS2: 5-aminolevulinate synthase activity (EC 2.3.1.37). This is the core, experimentally established function of the protein. Reason: This is the primary catalytic activity of ALAS2, backed by multiple experimental annotations and structural/kinetic characterization; conserved across the family. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000343737 SUPPORTS TRANSFER Seeded ancestral assertion retained against the conserved human mitochondrial catalytic function. The PAINT tree/MSA was not reconstructed; donor count and target self-evidence are not treated as defects. Supporting Evidence: PMID:32499479 ALAS catalyses the pyridoxal 5β²-phosphate (PLP)-dependent condensation of succinyl-CoA and glycine to form aminolevulinic acid (ALA), with CoA and CO2 as by-products |
| GO:0042541 hemoglobin biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: ALAS2 contributes the heme-synthesis branch of hemoglobin production in erythroid cells. Reason: The PAINT assertion at PTN000343740 is consistent with the conserved erythroid enzyme and the human catalytic evidence. GO:0042541 includes chemical pathways that form hemoglobin, including its heme component; it is not restricted to globin translation or final assembly. ALAS2 performs the first catalytic step in this biosynthetic supply, a defining role of the erythroid isozyme. Mouse donor provenance for hemoglobin biosynthesis is recorded in the MGI historical graph under PMID:9446639. Retain this established broader process as core without assigning globin synthesis to ALAS2. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000343740 SUPPORTS TRANSFER Seeded ancestral assertion retained against the conserved human erythroid heme contribution to hemoglobin synthesis. The PAINT tree/MSA was not reconstructed; donor count and target self-evidence are not treated as defects. Supporting Evidence: PMID:32499479 ALAS2 (gene location Xp11.21) is predominantly expressed in erythroid progenitor cells, and synthesizes 85β90% of total body heme specifically for hemoglobin production during erythropoiesis. |
| GO:0003870 5-aminolevulinate synthase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Combined automated mappings identify the defining ALAS2 catalytic reaction. Reason: The seeded EC:2.3.1.37 and RHEA:12921 mappings match the human PLP-dependent glycine/succinyl-CoA condensation measured in PMID:32499479. InterPro and mouse Alas2 sources are concordant; the internal conditions of ARBA00034153 were not independently reconstructed. The target judgment is grounded in direct human evidence. Propagation Review Root cause: NO FAILURE CORE Sources checked: ARBA:ARBA00034153 UNRESOLVED Rule ID preserved from the combined source; its internal conditions were not inspected. Direct human enzyme assays independently resolve the target activity. UniProtKB:P08680 SUPPORTS TRANSFER Mouse Alas2 erythroid ortholog, verified as P08680; the seeded Ensembl protein identifier is retained. Human import/catalytic evidence independently supports the conserved target assertion; the precise historic Compara donor experiment was not re-executed. ensembl:ENSMUSP00000066040 SUPPORTS TRANSFER Mouse Alas2 erythroid ortholog, verified as P08680; the seeded Ensembl protein identifier is retained. Human import/catalytic evidence independently supports the conserved target assertion; the precise historic Compara donor experiment was not re-executed. InterPro:IPR010961 SUPPORTS TRANSFER This exact domain/signature occurs in the immutable human UniProt record. The target inference is checked against human mitochondrial targeting and ALAS catalytic evidence; domain membership alone is not a substrate-specific assay. InterPro:IPR015118 SUPPORTS TRANSFER This exact domain/signature occurs in the immutable human UniProt record. The target inference is checked against human mitochondrial targeting and ALAS catalytic evidence; domain membership alone is not a substrate-specific assay. RHEA:12921 SUPPORTS TRANSFER Exact reaction is recorded in human UniProt: succinyl-CoA plus glycine yields ALA, CO2 and CoA; matches primary enzyme measurements. EC:2.3.1.37 SUPPORTS TRANSFER Exact ALAS catalytic class in human UniProt and primary structural/kinetic paper, not an inferred unrelated PLP reaction. Supporting Evidence: file:human/ALAS2/ALAS2-uniprot.txt succinyl-CoA + glycine + H(+) = 5-aminolevulinate + CO2 + CoA |
| GO:0005743 mitochondrial inner membrane | IEA GO_REF:0000044 | ACCEPT | Summary: The UniProt subcellular-location mapping places ALAS2 at the mitochondrial inner membrane. Reason: SL-0168 maps the curated peripheral inner-membrane location in the immutable UniProt record. The source states matrix-side association, not a transmembrane topology. Retain this correct source-level location; the precise membrane-association assay in PMID:14643893 is not resolved by its cached import abstract alone. Propagation Review Root cause: NO FAILURE CORE Sources checked: UniProtKB-SubCell:SL-0168 SUPPORTS TRANSFER SL-0168 maps the curated inner-membrane location; source explicitly specifies peripheral matrix-face association, not transmembrane insertion. Supporting Evidence: file:human/ALAS2/ALAS2-uniprot.txt Mitochondrion inner membrane PMID:14643893 the first 49 amino acids of the ALAS2 pre-protein are necessary and sufficient for translocation across the mitochondrial inner membrane |
| GO:0005759 mitochondrial matrix | IEA GO_REF:0000002 | ACCEPT | Summary: The ALAS presequence-family mapping places the catalytic enzyme in the mitochondrial matrix. Reason: IPR015118 is present in the human UniProt record. Mitochondrial import and the matrix-side catalytic reaction are independently supported by the human import study and Reactome:R-HSA-189442. This does not treat the presequence domain as a membrane anchor. Propagation Review Root cause: NO FAILURE CORE Sources checked: InterPro:IPR015118 SUPPORTS TRANSFER This exact domain/signature occurs in the immutable human UniProt record. The target inference is checked against human mitochondrial targeting and ALAS catalytic evidence; domain membership alone is not a substrate-specific assay. Supporting Evidence: file:human/ALAS2/ALAS2-uniprot.txt Localizes to the matrix side of the mitochondrion |
| GO:0006778 porphyrin-containing compound metabolic process | IEA GO_REF:0000002 | ACCEPT | Summary: Electronic (InterPro-based) assignment to a broad parent process. Heme is a porphyrin-containing compound and ALAS2 initiates its biosynthesis, so the term is correct although general. Reason: Accurate but non-specific parent of heme biosynthesis; acceptable as an IEA annotation. The more specific heme biosynthetic process term is also annotated. Propagation Review Root cause: NO FAILURE CORE Sources checked: InterPro:IPR015118 SUPPORTS TRANSFER This exact domain/signature occurs in the immutable human UniProt record. The target inference is checked against human mitochondrial targeting and ALAS catalytic evidence; domain membership alone is not a substrate-specific assay. Supporting Evidence: file:human/ALAS2/ALAS2-uniprot.txt Porphyrin-containing compound metabolism |
| GO:0016740 transferase activity | IEA GO_REF:0000002 | MODIFY | Summary: The PLP-dependent transferase domain mapping is consistent with ALAS2 chemistry but very general. Reason: IPR001917 is a class-II PLP-binding-site signature in the human record. The directly established glycine/succinyl-CoA condensation provides the more informative GO:0003870 replacement; the domain alone is not used to infer substrate specificity. Propagation Review Root cause: TERM SCOPING PROBLEM Sources checked: InterPro:IPR001917 SUPPORTS TRANSFER This exact domain/signature occurs in the immutable human UniProt record. The target inference is checked against human PLP binding/structural chemistry; domain membership alone is not a substrate-specific assay. Proposed replacements: 5-aminolevulinate synthase activity Supporting Evidence: file:human/ALAS2/ALAS2-uniprot.txt succinyl-CoA + glycine + H(+) = 5-aminolevulinate + CO2 + CoA |
| GO:0030170 pyridoxal phosphate binding | IEA GO_REF:0000002 | ACCEPT | Summary: Electronic (InterPro-based) assignment of PLP binding. ALAS2 is a PLP-dependent enzyme; PLP is covalently bound to active-site Lys391 as an internal aldimine. This is a correct secondary molecular function. Reason: Supported by the crystal structure and UniProt cofactor/binding-site annotations; PLP binding is intrinsic to catalysis. Propagation Review Root cause: NO FAILURE CORE Sources checked: InterPro:IPR004839 SUPPORTS TRANSFER This exact domain/signature occurs in the immutable human UniProt record. The target inference is checked against human PLP binding/structural chemistry; domain membership alone is not a substrate-specific assay. InterPro:IPR010961 SUPPORTS TRANSFER This exact domain/signature occurs in the immutable human UniProt record. The target inference is checked against human PLP binding/structural chemistry; domain membership alone is not a substrate-specific assay. InterPro:IPR015118 SUPPORTS TRANSFER This exact domain/signature occurs in the immutable human UniProt record. The target inference is checked against human PLP binding/structural chemistry; domain membership alone is not a substrate-specific assay. Supporting Evidence: PMID:32499479 PLP is covalently attached to the active site lysine (Lys391 in human ALAS2 (hsALAS2)) as an internal aldimine adduct |
| GO:0033014 tetrapyrrole biosynthetic process | IEA GO_REF:0000002 | ACCEPT | Summary: Electronic (InterPro-based) assignment to the broad tetrapyrrole biosynthesis parent. Heme is a tetrapyrrole and ALAS2 initiates its biosynthesis, so the term is correct though general. Reason: Accurate but non-specific parent of heme biosynthesis; acceptable for an IEA annotation alongside the more specific heme biosynthetic process term. Propagation Review Root cause: NO FAILURE CORE Sources checked: InterPro:IPR010961 SUPPORTS TRANSFER This exact domain/signature occurs in the immutable human UniProt record. The target inference is checked against human mitochondrial targeting and ALAS catalytic evidence; domain membership alone is not a substrate-specific assay. Supporting Evidence: PMID:32499479 The first and rate-limiting step is carried out by 5β²-aminolevulinate synthase (ALAS; EC 2.3.1.37) in the mitochondria |
| GO:0005515 protein binding | IPI PMID:25416956 A proteome-scale map of the human interactome network. | REMOVE | Summary: The seeded binary-interaction annotation links ALAS2 with BANP in a proteome-scale screen. Reason: Remove the uninformative GO:0005515 term under the generic-binding policy. PMID:25416956 describes systematic human interaction mapping, but the exact ALAS2-BANP supplementary result was not independently recovered and no specific mechanistic ALAS2 binding activity is established by the material examined. This is not a claim that the pair fails to interact. Supporting Evidence: PMID:25416956 a systematic map of ?14,000 high-quality human binary protein-protein interactions |
| GO:0005739 mitochondrion | IEA GO_REF:0000107 | ACCEPT | Summary: Electronic (Ensembl Compara) location transfer from the mouse ortholog placing ALAS2 in the mitochondrion. Correct compartment, corroborated by experimental data. Reason: Consistent with the mitochondrial localization of ALAS2 established experimentally and by the transit peptide. The proximate donor is mouse Alas2 P08680 / ENSMUSP00000066040, the erythroid ortholog, rather than the housekeeping paralog Alas1. Human import and catalytic assays independently support transfer. Propagation Review Root cause: NO FAILURE CORE Sources checked: UniProtKB:P08680 SUPPORTS TRANSFER Mouse Alas2 erythroid ortholog, verified as P08680; the seeded Ensembl protein identifier is retained. Human import/catalytic evidence independently supports the conserved target assertion; the precise historic Compara donor experiment was not re-executed. ensembl:ENSMUSP00000066040 SUPPORTS TRANSFER Mouse Alas2 erythroid ortholog, verified as P08680; the seeded Ensembl protein identifier is retained. Human import/catalytic evidence independently supports the conserved target assertion; the precise historic Compara donor experiment was not re-executed. Supporting Evidence: PMID:10727444 The first and the rate-limiting enzyme of heme biosynthesis is delta-aminolevulinate synthase (ALAS), which is localized in mitochondria |
| GO:0006783 heme biosynthetic process | IEA GO_REF:0000107 | ACCEPT | Summary: Electronic (Ensembl Compara) transfer from the mouse ortholog for heme biosynthetic process. This is a core process for ALAS2, which catalyzes the committed first step. Reason: Correct and consistent with the experimental and IBA annotations to the same term. The proximate donor is mouse Alas2 P08680 / ENSMUSP00000066040, the erythroid ortholog, rather than the housekeeping paralog Alas1. Human import and catalytic assays independently support transfer. Propagation Review Root cause: NO FAILURE CORE Sources checked: UniProtKB:P08680 SUPPORTS TRANSFER Mouse Alas2 erythroid ortholog, verified as P08680; the seeded Ensembl protein identifier is retained. Human import/catalytic evidence independently supports the conserved target assertion; the precise historic Compara donor experiment was not re-executed. ensembl:ENSMUSP00000066040 SUPPORTS TRANSFER Mouse Alas2 erythroid ortholog, verified as P08680; the seeded Ensembl protein identifier is retained. Human import/catalytic evidence independently supports the conserved target assertion; the precise historic Compara donor experiment was not re-executed. Supporting Evidence: PMID:32499479 The first and rate-limiting step is carried out by 5β²-aminolevulinate synthase (ALAS; EC 2.3.1.37) in the mitochondria |
| GO:0030218 erythrocyte differentiation | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: ALAS2-dependent heme supply supports late erythroid maturation. Reason: The Ensembl Compara source is mouse Alas2 P08680, with donor erythrocyte-differentiation IMP evidence traced to PMID:9446639 in the MGI historical graph. Its abstract distinguishes preserved early erythroid markers from reduced heme, globin and hemoglobinized cells. Conserved erythroid heme synthesis supports transfer of this contextual developmental contribution, retained as non-core. The evidence does not make ALAS2 an erythroid transcription factor or establish a heme-independent differentiation mechanism. Propagation Review Root cause: NO FAILURE NON CORE Sources checked: UniProtKB:P08680 SUPPORTS TRANSFER Mouse Alas2 erythroid ortholog, verified as P08680; the seeded Ensembl protein identifier is retained. MGI historical graph (2023-03-10) traces this process to IMP PMID:9446639; the primary abstract supports heme supply and late erythroid phenotype. ensembl:ENSMUSP00000066040 SUPPORTS TRANSFER Mouse Alas2 erythroid ortholog, verified as P08680; the seeded Ensembl protein identifier is retained. MGI historical graph (2023-03-10) traces this process to IMP PMID:9446639; the primary abstract supports heme supply and late erythroid phenotype. Supporting Evidence: PMID:32499479 ALAS2 (gene location Xp11.21) is predominantly expressed in erythroid progenitor cells, and synthesizes 85β90% of total body heme specifically for hemoglobin production during erythropoiesis |
| GO:0042541 hemoglobin biosynthetic process | IEA GO_REF:0000107 | ACCEPT | Summary: ALAS2 contributes the heme-synthesis branch of hemoglobin production in erythroid cells. Reason: The Ensembl Compara transfer from mouse Alas2 P08680 / ENSMUSP00000066040 is consistent with the conserved erythroid enzyme and the human catalytic evidence. GO:0042541 includes chemical pathways that form hemoglobin, including its heme component; it is not restricted to globin translation or final assembly. ALAS2 performs the first catalytic step in this biosynthetic supply, a defining role of the erythroid isozyme. Mouse donor provenance for hemoglobin biosynthesis is recorded in the MGI historical graph under PMID:9446639. Retain this established broader process as core without assigning globin synthesis to ALAS2. Propagation Review Root cause: NO FAILURE CORE Sources checked: UniProtKB:P08680 SUPPORTS TRANSFER Mouse Alas2 erythroid ortholog, verified as P08680; the seeded Ensembl protein identifier is retained. MGI historical graph (2023-03-10) traces this process to IMP PMID:9446639; the primary abstract supports heme supply and late erythroid phenotype. ensembl:ENSMUSP00000066040 SUPPORTS TRANSFER Mouse Alas2 erythroid ortholog, verified as P08680; the seeded Ensembl protein identifier is retained. MGI historical graph (2023-03-10) traces this process to IMP PMID:9446639; the primary abstract supports heme supply and late erythroid phenotype. Supporting Evidence: PMID:32499479 ALAS2 (gene location Xp11.21) is predominantly expressed in erythroid progenitor cells, and synthesizes 85β90% of total body heme specifically for hemoglobin production during erythropoiesis. |
| GO:0006785 heme B biosynthetic process | IDA PMID:2050125 Human erythroid 5-aminolevulinate synthase: promoter analysi... | ACCEPT | Summary: Human erythroid ALAS2 catalyzes the entry reaction of the heme B pathway. Reason: The cached PMID:2050125 abstract establishes human erythroid ALAS identity and its first-step heme pathway role. The precise IDA assignment is also preserved in GO-CAM 67369e7600001710, where ALAS2 activity is part of heme B biosynthesis. Retain this established core process with deference to the original full-text curation; the promoter/IRE assays are not misrepresented as a direct assay of the entire pathway. Supporting Evidence: PMID:2050125 5-Aminolevulinate synthase (ALAS) catalyzes the first step of the heme biosynthetic pathway |
| GO:0003870 5-aminolevulinate synthase activity | EXP PMID:34492704 The immunometabolite itaconate inhibits heme synthesis and r... | ACCEPT | Summary: ALAS2 catalysis is measured in the study of itaconyl-CoA inhibition. Reason: The cached full paper reports recombinant ALAS2 kinetic assays with succinyl-CoA/glycine and competitive inhibition by itaconyl-CoA, alongside human ALAS2 overexpression in mouse erythroleukemia cells. The detailed recombinant construct is delegated to supplementary Methods not recovered here. The EXP synthase assignment is consistent with these results and independent direct human enzyme measurements in PMID:32499479; it does not imply that the inflammatory model was assayed in human erythroblasts. Supporting Evidence: PMID:34492704 itaconyl-CoA is a competitive inhibitor of the erythroid-specific 5-aminolevulinate synthase (ALAS2), the first and rate-limiting step in heme synthesis PMID:34492704 itaconyl-CoA to be a competitive inhibitor of recombinant ALAS2 with an inhibitory constant of 100 Β± 20 ΞΌM |
| GO:0005739 mitochondrion | HTP PMID:34800366 Quantitative high-confidence human mitochondrial proteome an... | ACCEPT | Summary: The MitoCoP source supports the established mitochondrial compartment of ALAS2. Reason: PMID:34800366 combines quantitative fractionation, importomics and literature curation. The ALAS2-specific supplementary record was not independently recovered from the cached main text, so no enrichment or detection count is claimed. Accept the curated HTP mitochondrial assertion at its stated resolution, with independent human mitochondrial import/localization evidence from PMID:10727444 and PMID:14643893. Supporting Evidence: PMID:34800366 defined a mitochondrial high-confidence proteome of >1,100 proteins (MitoCoP) PMID:14643893 the first 49 amino acids of the ALAS2 pre-protein are necessary and sufficient for translocation across the mitochondrial inner membrane |
| GO:0003870 5-aminolevulinate synthase activity | IMP PMID:21252495 New mutation in erythroid-specific delta-aminolevulinate syn... | ACCEPT | Summary: The K156E patient variant severely reduces measured ALAS2 activity. Reason: The cached abstract of PMID:21252495 explicitly reports a continuous spectrophotometric enzyme assay and severe loss of activity for K156E. This is direct support for the seeded catalytic IMP, independently corroborated by human structural/kinetic work. Clinical pyridoxine responsiveness is not substituted for the enzyme assay. Supporting Evidence: PMID:21252495 X-linked SA, which results from mutations in erythroid-specific Ξ΄-aminolevulinate synthase (ALAS2), the first enzyme in heme biosynthesis PMID:21252495 A novel K156E substitution in ALAS2 was discovered in 1 pyridoxine-responsive patient. The functional study showed that this substitution severely decreases ALAS2 enzyme activity |
| GO:0003870 5-aminolevulinate synthase activity | IMP PMID:21309041 Sideroblastic anemia: molecular analysis of the ALAS2 gene i... | ACCEPT | Summary: Recombinant analysis of ten human ALAS2 missense variants supports the synthase function. Reason: PMID:21309041 explicitly reports expression in E. coli and in-vitro activity assays: five variants had reduced activity under standard conditions, while two others showed reduced activity without added PLP and increased thermosensitivity. Retain the catalytic IMP without claiming that all ten variants had the same defect. Supporting Evidence: PMID:21309041 XLSA is due to mutations in the erythroid-specific 5-aminolevulinate synthase (ALAS2) gene PMID:21309041 Five missense mutations resulted in decreased enzymatic activity under standard conditions |
| GO:0003870 5-aminolevulinate synthase activity | IMP PMID:21653323 ALAS2 acts as a modifier gene in patients with congenital er... | ACCEPT | Summary: The Y586F variant increases ALA release in a human ALAS2 modifier study. Reason: The primary abstract of PMID:21653323 reports faster ALA release by Y586F than wild-type ALAS2, directly supporting synthase activity. The clinical observation concerns a modifier in congenital erythropoietic porphyria caused by UROS variants; it does not make ALAS2 the primary cause of that disorder. Supporting Evidence: PMID:21653323 The rate of 5-aminolevulinate release from Y586F was significantly increased over that of wild-type ALAS2 |
| GO:0003870 5-aminolevulinate synthase activity | IDA PMID:32499479 Human aminolevulinate synthase structure reveals a eukaryoti... | ACCEPT | Summary: IDA annotation of 5-aminolevulinate synthase activity. Recombinant human ALAS2 was structurally and kinetically characterized (Km 31 uM succinyl-CoA, 11.8 uM glycine), directly demonstrating the PLP-dependent condensation of succinyl-CoA and glycine to form ALA. Reason: Direct in vitro demonstration of the core catalytic activity with a crystal structure of the human enzyme. Supporting Evidence: PMID:32499479 ALAS catalyses the pyridoxal 5β²-phosphate (PLP)-dependent condensation of succinyl-CoA and glycine to form aminolevulinic acid (ALA), with CoA and CO2 as by-products |
| GO:0003870 5-aminolevulinate synthase activity | IDA PMID:14643893 The major splice variant of human 5-aminolevulinate synthase... | ACCEPT | Summary: The major human exon-4-skipped ALAS2 isoform retains synthase activity. Reason: PMID:14643893 reports a functional exon-4-skipped isoform with slightly reduced catalytic activity and substantial erythroid expression. Both seeded IDA assertions are retained without favoring one submitting group. The result establishes tested isoform activity, not an activity exclusive to that isoform. Supporting Evidence: PMID:14643893 The initial step of the heme biosynthetic pathway in erythroid cells is catalyzed by an erythroid-specific isoform of 5-aminolevulinate synthase-2 (ALAS2) |
| GO:0003870 5-aminolevulinate synthase activity | IDA PMID:14643893 The major splice variant of human 5-aminolevulinate synthase... | ACCEPT | Summary: The major human exon-4-skipped ALAS2 isoform retains synthase activity. Reason: PMID:14643893 reports a functional exon-4-skipped isoform with slightly reduced catalytic activity and substantial erythroid expression. Both seeded IDA assertions are retained without favoring one submitting group. The result establishes tested isoform activity, not an activity exclusive to that isoform. Supporting Evidence: PMID:14643893 The initial step of the heme biosynthetic pathway in erythroid cells is catalyzed by an erythroid-specific isoform of 5-aminolevulinate synthase-2 (ALAS2) |
| GO:0005739 mitochondrion | IDA PMID:14643893 The major splice variant of human 5-aminolevulinate synthase... | ACCEPT | Summary: The human ALAS2 N-terminal sequence drives mitochondrial import. Reason: PMID:14643893 directly reports that the first 49 residues are necessary and sufficient for import across the inner membrane and that removal of exon 4 does not abolish mitochondrial targeting. This supports the broad mitochondrial localization at the source resolution. Supporting Evidence: PMID:14643893 the first 49 amino acids of the ALAS2 pre-protein are necessary and sufficient for translocation across the mitochondrial inner membrane |
| GO:0005759 mitochondrial matrix | TAS Reactome:R-HSA-189442 | ACCEPT | Summary: Reactome places the ALAS condensation reaction in the mitochondrial matrix. Reason: The recovered Reactome:R-HSA-189442 summary explicitly describes matrix-localized ALAS1/ALAS2 dimers catalyzing glycine/succinyl-CoA condensation. Retain the matrix location of ALAS2 catalysis independently of the source-specific uncertainty about its peripheral membrane attachment. Supporting Evidence: file:human/ALAS2/ALAS2-uniprot.txt Localizes to the matrix side of the mitochondrion |
| GO:0006879 intracellular iron ion homeostasis | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: Mouse Alas2 loss disrupts erythroid iron handling through deficient heme synthesis. Reason: The actual ISS donor is mouse Alas2 P08680. MGI traces its intracellular iron-homeostasis IMP to PMID:10562540: the primary abstract reports cytoplasmic iron accumulation in null embryonic cells and mitochondrial ring sideroblasts in adult chimeras. This supports a contextual contribution to iron utilization/homeostasis conserved with human sideroblastic disease, retained as non-core. ALAS2 is neither an iron transporter nor the ferrochelatase that inserts iron; its iron-responsive mRNA alone would not establish this process. Propagation Review Root cause: NO FAILURE NON CORE Sources checked: UniProtKB:P08680 SUPPORTS TRANSFER Mouse Alas2 erythroid ortholog, verified as P08680. The iron-homeostasis donor IMP traces to PMID:10562540 and measured iron accumulation in null mouse erythroid cells. Supporting Evidence: PMID:10562540 an abnormal hematopoietic cell fraction emerged that accumulated a large amount of iron diffusely in the cytoplasm. |
| GO:0032364 intracellular oxygen homeostasis | NAS PMID:16234850 Erythroid-specific 5-aminolevulinate synthase protein is sta... | UNDECIDED | Summary: Oxygen-dependent ALAS2 regulation is established, while intracellular oxygen homeostasis remains unresolved. Reason: GO:0032364 concerns maintenance of a steady intracellular oxygen level. The accessible PMID:16234850 abstract demonstrates oxygen-dependent protein stability, activity, vHL association and ubiquitination, but does not resolve how ALAS2 itself maintains that oxygen level. The full primary text was not recovered, so retain the source assertion as UNDECIDED rather than rejecting a possible additional homeostatic result or equating regulation of ALAS2 with oxygen homeostasis. Supporting Evidence: PMID:16234850 Hypoxia (1% O2) and inhibition of the proteasome increased both the stability and the specific activity of ALAS2 |
| GO:0001666 response to hypoxia | IDA PMID:16234850 Erythroid-specific 5-aminolevulinate synthase protein is sta... | KEEP AS NON CORE | Summary: Hypoxia stabilizes ALAS2 and increases its specific activity in an erythroid-cell model. Reason: PMID:16234850 explicitly reports the response to 1% oxygen in K562 cells and distinguishes normoxic vHL association. This supports the seeded response-to-hypoxia annotation as a contextual response, retained as non-core. The abstract suggests a prolyl-hydroxylase/vHL pathway but does not by itself demonstrate ALAS2 hydroxylation or oxygen-sensing activity. Supporting Evidence: PMID:16234850 Hypoxia (1% O2) and inhibition of the proteasome increased both the stability and the specific activity of ALAS2 |
| GO:0005515 protein binding | IPI PMID:16234850 Erythroid-specific 5-aminolevulinate synthase protein is sta... | REMOVE | Summary: FLAG-tagged ALAS2 associates with vHL under normoxia. Reason: The source abstract reports vHL co-immunoprecipitation with ALAS2 in normoxic cells and its loss under hypoxia. Remove the uninformative generic-binding annotation without denying the interaction. These data concern regulated ALAS2 stability; no specific adaptor or enzyme-inhibitor role for ALAS2 is established by the material examined. Supporting Evidence: PMID:16234850 The von Hippel-Lindau (vHL) protein was immunoprecipitated with FLAG epitope-tagged ALAS2 produced in normoxic cells |
| GO:0005515 protein binding | IPI PMID:10727444 Interaction between succinyl CoA synthetase and the heme-bio... | REMOVE | Summary: Human ALAS2 associates with the ATP-specific succinyl-CoA synthetase beta subunit. Reason: The full JCI Results/Methods of PMID:10727444 show human mature ALAS2 bait in yeast two-hybrid assays and tagged human proteins associating in CHO mitochondrial extracts. Remove generic GO:0005515 as uninformative while retaining this positive interaction evidence. Efficient succinyl-CoA use and import assistance are proposed explanations, not directly demonstrated channeling or adaptor activities that justify a replacement MF. Supporting Evidence: PMID:10727444 mitochodrially expressed SCS-betaA associates specifically with ALAS-E and not with ALAS-N |
| GO:0005739 mitochondrion | IDA PMID:10727444 Interaction between succinyl CoA synthetase and the heme-bio... | ACCEPT | Summary: Human ALAS2 constructs are recovered in mitochondrial fractions. Reason: Full PMID:10727444 Methods and Results examine human ALAS2 expressed in CHO cells, with mitochondrial preparations, precursor/mature forms and SUCLA2 co-immunoprecipitation. This supports mitochondrial localization in a heterologous mammalian host and agrees with the independent human import study; no new subcompartment precision is inferred from this assay. Supporting Evidence: PMID:10727444 The first and the rate-limiting enzyme of heme biosynthesis is delta-aminolevulinate synthase (ALAS), which is localized in mitochondria |
| GO:0006783 heme biosynthetic process | ISS GO_REF:0000024 | ACCEPT | Summary: The mouse erythroid ortholog supports conserved heme biosynthesis. Reason: The ISS donor is mouse Alas2 P08680; the MGI historical graph links its heme-biosynthesis IMP to PMID:9446639. Human ALAS2 catalysis and erythroid isoform assays independently establish the corresponding pathway contribution. Retain the conserved core process. Propagation Review Root cause: NO FAILURE CORE Sources checked: UniProtKB:P08680 SUPPORTS TRANSFER Mouse Alas2 erythroid ortholog, verified as P08680. MGI historical graph (2023-03-10) traces this process to IMP PMID:9446639; the primary abstract supports heme supply and late erythroid phenotype. Supporting Evidence: PMID:32499479 The first and rate-limiting step is carried out by 5β²-aminolevulinate synthase (ALAS; EC 2.3.1.37) in the mitochondria |
| GO:0006783 heme biosynthetic process | NAS PMID:14643893 The major splice variant of human 5-aminolevulinate synthase... | ACCEPT | Summary: The human splice-variant study supports erythroid heme biosynthesis. Reason: PMID:14643893 reports a substantial erythroid pool of catalytically active exon-4-skipped ALAS2. Its heme pathway contribution is consistent with the human reaction measurements; retain the NAS process assertion without claiming that splice-variant abundance alone is a complete flux assay. Supporting Evidence: PMID:14643893 The initial step of the heme biosynthetic pathway in erythroid cells is catalyzed by an erythroid-specific isoform of 5-aminolevulinate synthase-2 (ALAS2) |
| GO:0030218 erythrocyte differentiation | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: ALAS2-dependent heme supply supports late erythroid maturation. Reason: The curated ISS source is mouse Alas2 P08680, with donor erythrocyte-differentiation IMP evidence traced to PMID:9446639 in the MGI historical graph. Its abstract distinguishes preserved early erythroid markers from reduced heme, globin and hemoglobinized cells. Conserved erythroid heme synthesis supports transfer of this contextual developmental contribution, retained as non-core. The evidence does not make ALAS2 an erythroid transcription factor or establish a heme-independent differentiation mechanism. Propagation Review Root cause: NO FAILURE NON CORE Sources checked: UniProtKB:P08680 SUPPORTS TRANSFER Mouse Alas2 erythroid ortholog, verified as P08680. MGI historical graph (2023-03-10) traces this process to IMP PMID:9446639; the primary abstract supports heme supply and late erythroid phenotype. Supporting Evidence: PMID:32499479 ALAS2 (gene location Xp11.21) is predominantly expressed in erythroid progenitor cells, and synthesizes 85β90% of total body heme specifically for hemoglobin production during erythropoiesis |
| GO:0042541 hemoglobin biosynthetic process | ISS GO_REF:0000024 | ACCEPT | Summary: ALAS2 contributes the heme-synthesis branch of hemoglobin production in erythroid cells. Reason: The curated ISS transfer from mouse Alas2 P08680 is consistent with the conserved erythroid enzyme and the human catalytic evidence. GO:0042541 includes chemical pathways that form hemoglobin, including its heme component; it is not restricted to globin translation or final assembly. ALAS2 performs the first catalytic step in this biosynthetic supply, a defining role of the erythroid isozyme. Mouse donor provenance for hemoglobin biosynthesis is recorded in the MGI historical graph under PMID:9446639. Retain this established broader process as core without assigning globin synthesis to ALAS2. Propagation Review Root cause: NO FAILURE CORE Sources checked: UniProtKB:P08680 SUPPORTS TRANSFER Mouse Alas2 erythroid ortholog, verified as P08680. MGI historical graph (2023-03-10) traces this process to IMP PMID:9446639; the primary abstract supports heme supply and late erythroid phenotype. Supporting Evidence: PMID:32499479 ALAS2 (gene location Xp11.21) is predominantly expressed in erythroid progenitor cells, and synthesizes 85β90% of total body heme specifically for hemoglobin production during erythropoiesis. |
| GO:0005515 protein binding | IPI PMID:14643893 The major splice variant of human 5-aminolevulinate synthase... | REMOVE | Summary: The major ALAS2 splice variant retains interaction with SUCLA2. Reason: PMID:14643893 reports comparable SUCLA2 affinity for the exon-4-skipped and mature forms; the later human structure paper independently reports cross-linking with SUCLA2. Remove generic GO:0005515 as uninformative, without discounting either source as redundant or denying binding. A specific channeling or regulatory MF is not established by the interaction alone. Supporting Evidence: PMID:14643893 with affinity for the ATP-specific, beta subunit of succinyl CoA synthase, comparable to that of mature ALAS2. PMID:32499479 capable of forming an interaction with the previously reported partner, beta subunit (SUCLA2) of the succinyl-CoA synthetase complex |
| GO:0005743 mitochondrial inner membrane | IDA PMID:14643893 The major splice variant of human 5-aminolevulinate synthase... | ACCEPT | Summary: The curated human ALAS2 annotation places the mature enzyme at the inner membrane. Reason: Accept the established matrix-face peripheral association in UniProt and note the preserved IDA assertion in GO-CAM 67369e7600001710, which repeats the same PMID rather than supplying an independent assay. Defer to the original curator for the full PMID:14643893 localization evidence. Its accessible abstract directly establishes import across the inner membrane, which alone is not proof of stable membrane residency. This distinction is retained as an assay-access limitation, not used to overturn the curated compartment. Supporting Evidence: PMID:14643893 the first 49 amino acids of the ALAS2 pre-protein are necessary and sufficient for translocation across the mitochondrial inner membrane file:human/ALAS2/ALAS2-uniprot.txt Mitochondrion inner membrane CC {ECO:0000269|PubMed:14643893}; Peripheral membrane protein CC {ECO:0000305}. Note=Localizes to the matrix side of the mitochondrion CC inner membrane. |
| GO:0030218 erythrocyte differentiation | NAS PMID:2050125 Human erythroid 5-aminolevulinate synthase: promoter analysi... | KEEP AS NON CORE | Summary: Erythroid ALAS2 expression and heme production support maturation of the erythroid lineage. Reason: PMID:2050125 establishes the human erythroid promoter and iron-responsive mRNA, while independent mouse Alas2 perturbation evidence in PMID:9446639 links heme supply to late erythroid differentiation. Retain the seeded developmental process as non-core with this explicit division of evidence; promoter motifs alone do not establish that ALAS2 executes lineage specification. Supporting Evidence: PMID:2050125 putative erythroid-specific cis-acting elements including both a GATA-1 and an NF-E2 binding site |
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Download this section (compressed HTML)Q: What ALAS2-specific assay establishes stable peripheral inner-membrane attachment separately from import into the matrix, and does attachment differ among the documented splice isoforms?
Q: Does the ALAS2-SUCLA2 interaction channel succinyl-CoA under physiological erythroid conditions, or mainly organize/import the proteins?
Q: Does ALAS2 contribute experimentally to maintaining intracellular oxygen levels, beyond its documented oxygen-dependent stability and activity?
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