D-ribose 1-phosphate

1. purine nucleoside phosphorylase (nicotinamide)

Catalysed by PNPcytosol

1. adenosine:phosphate alpha-D-ribosyltransferase

Catalysed by PNPcytosol

1. uridine:phosphate alpha-D-ribosyltransferase

Catalysed by UPP2, UPP1cytosol

1. guanosine:phosphate alpha-D-ribosyltransferase

Catalysed by PNPcytosol

1. inosine:phosphate alpha-D-ribosyltransferase

Catalysed by PNPcytosol

1. D-Ribose 1,5-phosphomutase

Catalysed by PGM2cytosol

1. xanthosine:orthophosphate ribosyltransferase

Catalysed by PNPcytosol

1. purine nucleoside phosphorylase (nicotinamide)
2. 1-(beta-D-ribofuranosyl)-1,4-dihydronicotinamide + a quinone + H(+) = beta-nicotinamide D-riboside + a quinol

Catalysed by PNP, NQO2cytosol

1. purine nucleoside phosphorylase (nicotinamide)
2. ribosylnicotinamide kinase (nicotinamide ribonucleoside)

Catalysed by PNP, NMRK2, NMRK1cytosolOne of 2 routes

1. purine nucleoside phosphorylase (nicotinamide)
2. 1-(beta-D-ribofuranosyl)-1,4-dihydronicotinamide + a quinone + H(+) = beta-nicotinamide D-riboside + a quinol
3. 2 a quinone + NADPH + H(+) = 2 a 1,4-benzosemiquinone + NADP(+)

Catalysed by PNP, NQO2, CRYZ, TP53I3 and 2 morecytosol

1. D-Ribose 1,5-phosphomutase
2. D-ribose-5-phosphate aldose-ketose-isomerase
3. D-ribulose 5-phosphate + CTP + H(+) = CDP-D-ribulose + diphosphate