KCR1 (At1g67730; Q8L9C4) review notes

Identity and function

• Beta-ketoacyl-CoA reductase of the ER FAE; only functional KCR isoform PMID:19439572.
• Complements yeast ybr159 KCR mutant PMID:11792704; ybr159 microsomes defective in beta-ketoacyl reduction.
• ER localization of functional YFP-KCR1 PMID:19439572; dilysine ER retention motif.
• Null kcr1 embryo lethal (globular arrest); RNAi reduces wax and VLCFAs of sphingolipids, seed TAG, root glycerolipids PMID:19439572.
• KCR2 (At1g24470) is inactive in yeast and cannot rescue kcr1.
• Cofactor: paper notes putative NADH-binding site; deep research (file:ARATH/KCR1/KCR1-deep-research-falcon.md) flags NADH vs NADPH preference as unmeasured. GO:0141040 is written with NADP+.

Decisions

• MODIFY: acetoacetyl-CoA reductase activity (GO:0018454, IMP) -> GO:0141040 very-long-chain 3-oxoacyl-CoA reductase activity.
• ACCEPT: GO:0141040 (EXP, IEA), ketoreductase (IBA, IDA; general but correct - kept consistent across evidence codes), ER/ER membrane, VLCFA biosynthesis (IMP), IEA parents.
• KEEP_AS_NON_CORE: embryo development (IMP).
• MARK_AS_OVER_ANNOTATED: mitochondrion (HDA, co-fractionation).
• REMOVE: chloroplast (ISM), protein binding (IPI, PMID:30604175; uninformative).
• No NEW terms. Considered NEW wax biosynthetic process (RNAi reduces wax) but not added - evidence is supportive but KCR1 is a generic elongase subunit and VLCFA biosynthesis already captures it.