Molecular characteristics of phosphoinositide binding

Phosphoinositides in general and phosphatidylinositol 4,5-bisphosphate (PI(4,5)P₂ or PIP₂) in particular have been recently found to function as important regulators of ion channels. Yet, while specific residues have been identified that affect channel-PIP₂ interactions, the precise binding site of PIP₂ has not been determined in any case. In addition to binding ion channels, however, phosphoinositides interact with a plethora of other proteins, and in a number of cases, the crystallographic structures of the complexes have been determined. Based on a database of 25 complexed crystallographic structures, we have addressed the molecular characteristics of phosphoinositide binding to proteins. Implications to phosphoinositide binding to ion channels are also discussed.