The Saccharomyces cerevisiae ISN1 (YOR155c) gene encodes an IMP-specific 5'-nucleotidase, which catalyses degradation of IMP to inosine as part of the purine salvage pathway.

1: The yeast ISN1 (YOR155c) gene encodes a new type of IMP-specific 5'-nucleotidase. Itoh R, Saint-Marc C, Chaignepain S, Katahira R, Schmitter JM, Daignan-Fornier B; 0;0:0-0. PMID:12735798