ILV2 notes (YMR108W, P07342)

Evidence journal for the review; module context: branched-chain amino acid biosynthesis.

• Ilv2 is the catalytic subunit of mitochondrial acetohydroxyacid synthase (AHAS, EC 2.2.1.6) [UniProt:P07342].
• AHAS catalyses the first common step of BCAA synthesis PMID:16390333
• Two reactions: 2 pyruvate -> 2-acetolactate (Val/Leu) and pyruvate + 2-oxobutanoate -> 2-aceto-2-hydroxybutanoate (Ile) [UniProt:P07342, RHEA:25249, RHEA:27654].
• Recombinant Ilv2 is active alone; Ilv6 stimulates it PMID:10213630.
• Cofactors ThDP, Mg2+, FAD PMID:15709745; crystal structures with sulfonylurea herbicides PMID:15709745.
• Location: mitochondrion (multiple proteomics HDA; UniProt).

Curation observations

• PMID:2406721 (cited by SGD for IDA and IMP BCAA biosynthesis) is a protein N-myristoylation/NMT1 study; the abstract does not mention ILV2. Accepted on independent evidence; flagged as a possible reference mis-mapping (full text not cached).
• No GO:1901705 L-isoleucine biosynthetic process on ILV2, although ILV5/ILV3/BAT1/BAT2 and the ComplexPortal AHAS complex carry it (QuickGO, 2026-10). Proposed as NEW (IC): Ilv2 catalyses step 1 of the Ile branch.
• YeastPathways appears to assign the AHAS reaction to the complex rather than to ILV2 (no RCA rows on ILV2).