Synthesis of an inositol hexakisphosphate (IP6) affinity probe to study the interactome from a colon cancer cell line

Abstract

Inositol hexakisphosphate (InsP₆ or IP₆) is an important signalling molecule in vesicular trafficking, neurotransmission, immune responses, regulation of protein kinases and phosphatases, activation of ion channels, antioxidant functions and anticancer activities. An IP₆ probe was synthesised from myo-inositol via a derivatised analogue, which was immobilised through a terminal amino group onto Dynabeads. Systematic analysis of the IP₆ interactome has been performed using the IP₆ affinity probe using cytosolic extracts from the LIM1215 colonic carcinoma cell line. LC/MS/MS analysis identified 77 proteins or protein complexes that bind to IP₆ specifically, including AP-2 complex proteins and β-arrestins as well as a number of novel potential IP₆ interacting proteins. Bioinformatic enrichment analysis of the IP₆ interactome reinforced the concept that IP₆ regulates a number of biological processes including cell cycle and division, signal transduction, intracellular protein transport, vesicle-mediated transport and RNA splicing.