D-ribose 5-phosphate

1. D-ribose 5-phosphate + CTP + H(+) = CDP-D-ribose + diphosphate

Catalysed by CRPPA

1. D-ribose + ATP = D-ribose 5-phosphate + ADP + H(+)

Catalysed by RBKS

1. alpha-D-ribose 1-phosphate = D-ribose 5-phosphate

Catalysed by PGM2

1. D-ribose 5-phosphate + ATP + H(+) = ADP-D-ribose + diphosphate

Catalysed by NUDT5

1. D-ribose 5-phosphate + ATP = 5-phospho-alpha-D-ribose 1-diphosphate + AMP + H(+)

Catalysed by PRPS2, PRPS1L1, PRPS1

1. D-ribose 5-phosphate + ATP = 5-phospho-alpha-D-ribose 1-diphosphate + AMP + H(+)
2. Nicotinate-nucleotide:pyrophosphate phosphoribosyltransferase (carboxylating)

Catalysed by PRPS2, PRPS1L1, PRPS1, QPRTcytosolOne of 2 routes

1. D-ribose 5-phosphate + ATP = 5-phospho-alpha-D-ribose 1-diphosphate + AMP + H(+)
2. Orotidine-5'-phosphate:diphosphate phospho-alpha-D-ribosyl-transferase

Catalysed by PRPS2, PRPS1L1, PRPS1

1. D-ribose 5-phosphate + ATP = 5-phospho-alpha-D-ribose 1-diphosphate + AMP + H(+)
2. phosphoribosyl pyrophosphate amidotransferase (glutamine)
3. 5-phospho-beta-D-ribosylamine + glycine + ATP = N(1)-(5-phospho-beta-D-ribosyl)glycinamide + ADP + phosphate + H(+)

Catalysed by PRPS2, PRPS1L1, PRPS1, PPAT and 1 morecytosol

1. D-ribose 5-phosphate + ATP = 5-phospho-alpha-D-ribose 1-diphosphate + AMP + H(+)
2. nicotinamide-D-ribonucleotide:diphosphate phospho-alpha-D-ribosyltransferase
3. 5'-nucleotidase (nicotinamide D-ribonucleotide)