In enzymology, a nicotinate phosphoribosyltransferase (EC 6.3.4.21) is an enzyme that catalyzes the chemical reaction

nicotinate + 5-phospho-α-D-ribose 1-diphosphate + ATP + H₂O ${\displaystyle \rightleftharpoons }$ nicotinate D-ribonucleotide + diphosphate + ADP + phosphate

Thus, the four substrates of this enzyme are nicotinate, 5-phospho-alpha-D-ribose 1-diphosphate, ATP, and H₂O, whereas its four products are nicotinate D-ribonucleotide, diphosphate, ADP, and phosphate.

This enzyme belongs to the family of ligases, specifically those forming generic carbon-nitrogen bonds. The systematic name of this enzyme class is 5-phospho-alpha-D-ribose 1-diphosphate:nicotinate ligase (ADP, diphosphate-forming) .

As of late 2007, 7 structures have been solved for this class of enzymes, with PDB accession codes 1VLP, 1YBE, 1YIR, 1YTD, 1YTE, 1YTK, and 2F7F.