Extended Data Fig. 7: Validation of IP6 identification and interactions.
From: InsP6 binding to PIKK kinases revealed by the cryo-EM structure of an SMG1–SMG8–SMG9 complex
Validation of IP6 identification and interactions. (a) The SMG1 complex was analyzed by ion pair HPLC-MS (top and middle panels). To validate the identity of the 658.85 Da mass, this ligand was fragmented and the daughter ions analyzed by a second MS (bottom panel). As expected, the masses of the fragmented ions reflect a loss of individual groups of phosphate and water. (b) The chemical formula, composition and the monoisotopic mass (observed and expected) of each daughter ion. (c) Diagram of the chemical environment of IP6 bound to SMG1, showing the distances between the IP6 phosphate oxygens and the amino groups of SMG1 lysine and arginine side chains measured from the atomic model. We note, however, that the precision of these measurements is limited by the resolution of the electron density map.
