RNR3 (P21672) notes

Module: dntp_de_novo_synthesis, role = alternative large (R1/alpha) subunit of class Ia RNR.

Evidence journal

• Alternative, non-essential large subunit, ~80% identical to Rnr1; high-copy RNR3 suppresses rnr1 PMID:2199320
• Very low intrinsic activity, activated with Rnr1 [PMID:11893751 "The in vitro activity of Rnr3 was less than 1% of the Rnr1 activity."; "a strong synergism between Rnr3 and Rnr1 was observed"]
• Cytoplasmic, detectable only after HU/MMS or in crt1 PMID:12732713
• UniProt: allosteric specificity/activity sites on the large subunit (by similarity) [UniProt:P21672]

Annotation decisions

• RNR activity (IDA contributes_to, IEA, RCA) ACCEPT; ATP binding KEEP_AS_NON_CORE (allosteric site).
• Mitochondrion HDA x2: KEEP_AS_NON_CORE; no evidence for intramitochondrial RNR in yeast.
• GO:0106387 'de novo' GMP biosynthesis (RCA from YeastPathways PWY-7222-1): REMOVE, pathway-to-GO mapping error (RNR makes dGDP).

Module/YeastCyc observations

• YeastCyc lists RNR1-4 on every NDP reduction step including several purine superpathways; fine for the complex, but the GO-CAM conversion of PWY-7222-1 uses GO:0106387 (GMP) as the process.