De novo inosine monophosphate biosynthesis

Exact UniProt exemplars delimit each reaction role without restricting the module taxonomically. A multidomain protein may satisfy more than one leaf: GART combines PurD-, PurN-, and PurM-like roles, PAICS combines direct AIR carboxylase and SAICAR synthetase roles, and PurH/ATIC commonly combines the final two reactions. GART remains an exact fusion exemplar on the PurD and PurN leaves, where its reviewed domain descriptions establish those activities without using its whole-protein family as a reaction selector. The PurM leaf uses PTHR10520:SF12 because that whole-protein subfamily contains both standalone bacterial PurM proteins and the GART fusion; the leaf molecular function constrains it to the shared cyclo-ligase role. Separate bacterial and eukaryotic adenylosuccinate-lyase families are retained for the PurB leaf. Parent PANTHER families containing both standalone enzymes and fusion proteins are selector scaffolds constrained by the leaf molecular function and exemplars. No ancestral PTN node is asserted without verified PAINT IBD evidence.

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