Regulatory (small) subunit of mitochondrial acetohydroxyacid synthase (AHAS; acetolactate synthase) in Saccharomyces cerevisiae. Ilv6 has no catalytic activity of its own; it binds the catalytic subunit Ilv2 to form the heterotetrameric AHAS holoenzyme, stimulating Ilv2 activity up to ~7-10-fold and conferring end-product feedback inhibition by valine. A fungal-specific sequence insert in Ilv6 forms an MgATP-binding site, and MgATP binding reverses valine inhibition. Ilv6 is imported into mitochondria with removal of a transit peptide, where AHAS catalyses the first common step of isoleucine, leucine and valine biosynthesis. Deletion of ILV6 causes no obvious growth phenotype but abolishes valine feedback inhibition of AHAS.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003984 acetolactate synthase activity | IDA PMID:16390333 Mutations in the regulatory subunit of yeast acetohydroxyaci... | ACCEPT | Summary: contributes_to acetolactate synthase activity: Ilv6 is non-catalytic but enhances Ilv2 activity within the holoenzyme; the contributes_to qualifier is appropriate. Core. Supporting Evidence: PMID:10213630 Reconstitution studies showed that the ilv6 protein stimulates the catalytic activity of the ilv2 protein by up to 7-fold PMID:16390333 This heterotetrameric enzyme is composed of a larger subunit that contains the catalytic machinery and a smaller subunit that plays a regulatory role. |
| GO:0003984 acetolactate synthase activity | IDA PMID:8972574 Functional analysis of YCL09C: evidence for a role as the re... | ACCEPT | Summary: contributes_to AHAS activity; deletion abolishes valine feedback inhibition of yeast AHAS, showing Ilv6 is part of the active enzyme in vivo. Supporting Evidence: PMID:8972574 Using a yeast strain carrying a complete deletion of YCL09C, we have observed the loss of such retro-inhibition. PMID:16390333 This heterotetrameric enzyme is composed of a larger subunit that contains the catalytic machinery and a smaller subunit that plays a regulatory role. |
| GO:0003984 acetolactate synthase activity | IMP PMID:16390333 Mutations in the regulatory subunit of yeast acetohydroxyaci... | ACCEPT | Summary: contributes_to AHAS activity supported by mutational analysis of Ilv6 affecting activation of Ilv2. Supporting Evidence: PMID:16390333 Five of the mutations abolished MgATP activation and are suggested to constitute the binding site for this modulator. PMID:16390333 This heterotetrameric enzyme is composed of a larger subunit that contains the catalytic machinery and a smaller subunit that plays a regulatory role. |
| GO:0005515 protein binding | IPI PMID:16429126 Proteome survey reveals modularity of the yeast cell machine... | REMOVE | Summary: High-throughput interaction with the Hsp70 Ssa2 (proteome-wide complex purification). Uninformative protein binding term; a chaperone association does not describe Ilv6 function. Reason: Generic protein binding with the cytosolic Hsp70 Ssa2 from a high-throughput screen, likely reflecting chaperone handling of the precursor; it conveys no information about Ilv6 function. Removal does not imply the interaction is false. Supporting Evidence: PMID:16429126 Proteome survey reveals modularity of the yeast cell machinery. |
| GO:0005515 protein binding | IPI PMID:37968396 The social and structural architecture of the yeast protein ... | REMOVE | Summary: High-throughput interactome detection of Ilv6-Ssa2. Uninformative protein binding term. Reason: Generic protein binding with the cytosolic Hsp70 Ssa2 from a high-throughput screen, likely reflecting chaperone handling of the precursor; it conveys no information about Ilv6 function. Removal does not imply the interaction is false. Supporting Evidence: PMID:37968396 The social and structural architecture of the yeast protein interactome. |
| GO:0005737 cytoplasm | IEA GO_REF:0000117 | MODIFY | Summary: ARBA cytoplasm annotation. Not wrong under GO's definition of cytoplasm (which includes mitochondria) but uninformative; Ilv6 is a mitochondrial matrix protein. Reason: Replace with the specific, experimentally supported compartment. Proposed replacements: mitochondrion Supporting Evidence: PMID:10213630 YCL009c was shown to be expressed in yeast and the protein localized in mitochondria where it undergoes removal of a transit peptide targeting sequence. |
| GO:0005739 mitochondrion | HDA PMID:14576278 The proteome of Saccharomyces cerevisiae mitochondria. | ACCEPT | Summary: Mitochondrial proteome HDA; consistent with direct localization data. Supporting Evidence: PMID:14576278 The proteome of Saccharomyces cerevisiae mitochondria. PMID:10213630 YCL009c was shown to be expressed in yeast and the protein localized in mitochondria where it undergoes removal of a transit peptide targeting sequence. |
| GO:0005739 mitochondrion | HDA PMID:16823961 Toward the complete yeast mitochondrial proteome: multidimen... | ACCEPT | Summary: Mitochondrial proteome HDA; consistent with direct localization data. Supporting Evidence: PMID:16823961 Toward the complete yeast mitochondrial proteome: multidimensional separation techniques for mitochondrial proteomics. PMID:10213630 YCL009c was shown to be expressed in yeast and the protein localized in mitochondria where it undergoes removal of a transit peptide targeting sequence. |
| GO:0005739 mitochondrion | HDA PMID:24769239 Quantitative variations of the mitochondrial proteome and ph... | ACCEPT | Summary: Mitochondrial proteome HDA; consistent with direct localization data. Supporting Evidence: PMID:24769239 Quantitative variations of the mitochondrial proteome and phosphoproteome during fermentative and respiratory growth in Saccharomyces cerevisiae. PMID:10213630 YCL009c was shown to be expressed in yeast and the protein localized in mitochondria where it undergoes removal of a transit peptide targeting sequence. |
| GO:0005739 mitochondrion | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular-location mapping; correct. Supporting Evidence: PMID:10213630 YCL009c was shown to be expressed in yeast and the protein localized in mitochondria where it undergoes removal of a transit peptide targeting sequence. |
| GO:0005739 mitochondrion | NAS PMID:16390333 Mutations in the regulatory subunit of yeast acetohydroxyaci... | ACCEPT | Summary: Author statement; consistent with direct localization data. Supporting Evidence: PMID:10213630 YCL009c was shown to be expressed in yeast and the protein localized in mitochondria where it undergoes removal of a transit peptide targeting sequence. |
| GO:0005948 acetolactate synthase complex | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA for AHAS complex membership; Ilv6 is the small subunit. Supporting Evidence: PMID:16390333 This heterotetrameric enzyme is composed of a larger subunit that contains the catalytic machinery and a smaller subunit that plays a regulatory role. PMID:10213630 Reconstitution studies showed that the ilv6 protein stimulates the catalytic activity of the ilv2 protein by up to 7-fold |
| GO:0005948 acetolactate synthase complex | IDA PMID:10213630 Expression, purification, characterization, and reconstituti... | ACCEPT | Summary: Reconstitution of the Ilv2-Ilv6 complex from purified subunits. Supporting Evidence: PMID:10213630 Reconstitution studies showed that the ilv6 protein stimulates the catalytic activity of the ilv2 protein by up to 7-fold PMID:10213630 Under optimal conditions for reconstitution, a dissociation constant for the subunits of 70 +/- 7 nM was determined. |
| GO:0005948 acetolactate synthase complex | IPI PMID:16390333 Mutations in the regulatory subunit of yeast acetohydroxyaci... | ACCEPT | Summary: Ilv6 is the regulatory subunit of the heterotetrameric AHAS holoenzyme. Supporting Evidence: PMID:16390333 This heterotetrameric enzyme is composed of a larger subunit that contains the catalytic machinery and a smaller subunit that plays a regulatory role. |
| GO:0009082 branched-chain amino acid biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA; as an integral AHAS subunit Ilv6 participates in the first step of BCAA biosynthesis. Core process. Supporting Evidence: PMID:16390333 Isoleucine, leucine and valine are synthesized via a common pathway in which the first reaction is catalysed by AHAS (acetohydroxyacid synthase; EC 2.2.1.6). PMID:16390333 This heterotetrameric enzyme is composed of a larger subunit that contains the catalytic machinery and a smaller subunit that plays a regulatory role. |
| GO:0009082 branched-chain amino acid biosynthetic process | IDA PMID:16390333 Mutations in the regulatory subunit of yeast acetohydroxyaci... | ACCEPT | Summary: Ilv6 stimulates and regulates the enzyme that catalyses the first common BCAA step. Supporting Evidence: PMID:16390333 Isoleucine, leucine and valine are synthesized via a common pathway in which the first reaction is catalysed by AHAS (acetohydroxyacid synthase; EC 2.2.1.6). PMID:16390333 Five of the mutations abolished MgATP activation and are suggested to constitute the binding site for this modulator. |
| GO:0009082 branched-chain amino acid biosynthetic process | IDA PMID:8972574 Functional analysis of YCL09C: evidence for a role as the re... | ACCEPT | Summary: Ilv6 is the regulatory subunit of yeast AHAS, the first BCAA biosynthetic enzyme. Supporting Evidence: PMID:8972574 Using a yeast strain carrying a complete deletion of YCL09C, we have observed the loss of such retro-inhibition. PMID:8972574 These results together with the computational predictions show that YCL09C encodes the regulatory subunit of yeast acetolactate synthase. |
| GO:0009082 branched-chain amino acid biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: Electronic annotation consistent with experimental data. Supporting Evidence: PMID:16390333 Isoleucine, leucine and valine are synthesized via a common pathway in which the first reaction is catalysed by AHAS (acetohydroxyacid synthase; EC 2.2.1.6). |
| GO:0009099 L-valine biosynthetic process | IEA GO_REF:0000041 | ACCEPT | Summary: UniPathway mapping (valine biosynthesis step 1). Ilv6 is a subunit of the enzyme for this step and mediates valine feedback control. Supporting Evidence: PMID:16390333 Isoleucine, leucine and valine are synthesized via a common pathway in which the first reaction is catalysed by AHAS (acetohydroxyacid synthase; EC 2.2.1.6). PMID:10213630 confers upon it sensitivity to inhibition by valine |
| GO:0030234 enzyme regulator activity | IBA GO_REF:0000033 | TOO GENERAL | Summary: PAINT IBA for enzyme regulator activity; correct but general. The specific term acetolactate synthase regulator activity exists and is already applied electronically. Reason: Correct but general parent of acetolactate synthase regulator activity (GO:1990610), which Ilv6 already carries and which is captured in core_functions. Supporting Evidence: PMID:10213630 Reconstitution studies showed that the ilv6 protein stimulates the catalytic activity of the ilv2 protein by up to 7-fold PMID:10213630 confers upon it sensitivity to inhibition by valine |
| GO:0030234 enzyme regulator activity | IDA PMID:8972574 Functional analysis of YCL09C: evidence for a role as the re... | TOO GENERAL | Summary: Experimental evidence that Ilv6 regulates AHAS (loss of valine feedback inhibition on deletion). Specific child term preferred. Reason: Correct but general parent of acetolactate synthase regulator activity (GO:1990610), which Ilv6 already carries and which is captured in core_functions. Supporting Evidence: PMID:8972574 Using a yeast strain carrying a complete deletion of YCL09C, we have observed the loss of such retro-inhibition. |
| GO:0042645 mitochondrial nucleoid | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: PAINT IBA for mitochondrial nucleoid (is_active_in), seeded only by the yeast IDA. Plausible localization but not related to the AHAS function. Reason: Mitochondrial nucleoid association was detected in a screen for mtDNA-associated proteins; the abstract does not describe a functional role for Ilv6 in mtDNA maintenance, so this is retained as a non-core localization (deferring to the curator on the full-text evidence). Supporting Evidence: PMID:15692048 We have identified 22 mtDNA-associated proteins in yeast |
| GO:0042645 mitochondrial nucleoid | IDA PMID:15692048 Aconitase couples metabolic regulation to mitochondrial DNA ... | KEEP AS NON CORE | Summary: Ilv6 was among proteins identified in purified mtDNA nucleoids. Deferring to the curator on the full-text evidence; non-core. Reason: Mitochondrial nucleoid association was detected in a screen for mtDNA-associated proteins; the abstract does not describe a functional role for Ilv6 in mtDNA maintenance, so this is retained as a non-core localization (deferring to the curator on the full-text evidence). Supporting Evidence: PMID:15692048 We have identified 22 mtDNA-associated proteins in yeast |
| GO:1990610 acetolactate synthase regulator activity | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro-based acetolactate synthase regulator activity; this is the precise description of Ilv6 molecular function (stimulation of Ilv2 and conferral of valine inhibition and MgATP activation). Core. Supporting Evidence: PMID:10213630 Reconstitution studies showed that the ilv6 protein stimulates the catalytic activity of the ilv2 protein by up to 7-fold PMID:10213630 confers upon it sensitivity to inhibition by valine PMID:8972574 Using a yeast strain carrying a complete deletion of YCL09C, we have observed the loss of such retro-inhibition. PMID:16390333 Five of the mutations abolished MgATP activation and are suggested to constitute the binding site for this modulator. |
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Download this section (compressed HTML)Regulatory subunit of acetolactate synthase; acetolactate synthase catalyzes the first step of branched-chain amino acid biosynthesis; enhances activity of the Ilv2p catalytic subunit, localizes to mitochondria
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