Inositol polyphosphates intersect with signaling and metabolic networks via two distinct mechanisms

Significance Inositol polyphosphates and pyrophosphates are ubiquitous eukaryotic messengers and are involved in numerous cellular processes, including insulin signaling and cell migration. Nevertheless, annotation of the specific signaling events underlying these processes has been stymied by the lack of suitable tools. By applying chemically synthesized affinity reagents, we comprehensively annotated inositol polyphosphate binding proteins in the model organism Saccharomyces cerevisiae , revealing a role for these molecules in nucleotide metabolism, ribosome biogenesis, and phosphorylation-based signaling. Furthermore, the reagents enabled the magnesium-dependent isolation of targets of protein pyrophosphorylation, a posttranslational modification mediated by the inositol pyrophosphates. The protein targets are diverse in function and highlight the complex regulation of cellular signaling and metabolic networks by inositol pyrophosphates.