GA3 (ent-kaurene oxidase, KO, CYP701A3; At5g25900; UniProt Q93ZB2) - curation notes

• Folder symbol GA3 (TAIR symbol; UniProt primary gene name is KO, synonyms CYP701A3/GA3/KO1). Accession Q93ZB2 = KO1_ARATH verified.
• Falcon deep research attempted and failed (exit code 1).

Function

• Three oxidations ent-kaurene -> ent-kaurenoic acid (RHEA:32323) PMID:9952446.
• ga3-1 lacks KO activity; genomic complementation PMID:9671797.
• Mechanism: intermediates retained, first hydroxylation rate-limiting PMID:20698828.

Location

• Outer face of chloroplast envelope PMID:11722763; LOPIT proteomics place it with ER markers [PMID:16618929, PMID:22923678]. Recorded as an open question (plastid envelope vs ER vs contact sites).

Curation decisions

• Generic P450 MF terms (monooxygenase, GO:0016705, GO:0016709 IBA) -> MODIFY to GO:0052615.
• oxygen binding IMP (TIGR legacy) -> MODIFY to GO:0052615 (mutant shows loss of KO activity, not O2 binding).
• iron ion binding over-annotated (heme iron); heme binding non-core.