Structural characterization of the interaction between a Pleckstrin homology domain and phosphatidylinositol 4,5-bisphosphate

Abstract

The pleckstrin homology (PH) domain is a protein module of approximately 100 amino acids

that is found in several proteins involved in signal transduction [for a recent review, see Gibson et al.

(1994) Trends Biochem. Sci. 19,349-3531. Although the specific function of the PH domain has not yet

been elucidated, many of the proteins which contain this domain associate with phospholipid membranes,

and PH domains have been shown to bind to phosphatidylinositol 4,5-bisphosphate (PIP2) [Harlan et al.

(1994) Nature 371, 168-1701 and the by subunits of G-proteins [Touhara et al. (1994) J. Biol. Chem.

269, 10217- 102201. We have postulated that pleckstrin homology domains may be important for the

translocation of proteins to the membrane by an interaction with the negatively charged head group of

phospholipids. Here we show the importance of three conserved lysine residues for binding to PIP2 by

site-directed mutagenesis. These results should aid future site-directed mutagenesis studies in probing

the function of PIP2-PH domain interactions in the various proteins containing this module. In addition,

we examine the specificity of this binding and illustrate the importance of charge-charge interactions in

PIP2-PH domain complex formation from binding experiments involving PIP2 analogs.