Phosphoinositides as ligands of PHD-fingers: implications for chromatin remodeling

摘要

Phosphatidylinositol phosphates (PtdInsPs) play critical roles in signal transduction pathways, cytoskele-tal regulation, and vesicular trafficking and are implicated in multiple disease pathways. In the nucleus, PtdlnsPs have been found associated with chromatin, but their specific nuclear-binding proteins have not been identified. In a biochemical screen for PtdInsP-binding proteins, we identified a protein (ING2) containing a Plant Homeodomain (PHD) finger, a motif present in many chromatin- regulatory proteins. We show that the PHD domains of ING2 and of other diverse nuclear proteins bind to the rare PtdInsP species, phosphatidylinositol 5-phosphate (PtdIns(5)P). Further, we provide evidence for a functional