Protein Pyrophosphorylation by Diphosphoinositol Pentakisphosphate (InsP7)
Diphosphoinositol polyphosphates, also known as inositol pyrophosphates, are a family of water soluble inositol phosphates that possess diphosphate or pyrophosphate moieties. In the presence of divalent cations such as Mg2+, the “high energy” β phosphate can be transferred from the inositol pyrophosphates, InsP 7 and InsP 8, to prephosphorylated serine residues on proteins, to form pyrophosphoserine. This chapter provides detailed methods to identify proteins that are substrates for pyrophosphorylation by InsP 7, conduct phosphorylation assays on purified protein, and detect protein pyrophosphorylation.
Key wordsInositol pyrophosphate Diphosphoinositol pentakisphosphate Pyrophosphoserine Pyrophosphorylation Phosphorylation
We thank Adolfo Saiardi and Solomon H. Snyder for suggestions and helpful comments. This work is supported by the Department of Biotechnology, Government of India, and The Wellcome Trust, UK.