The Solution Structure and Dynamics of the Pleckstrin Homology Domain of G Protein-coupled Receptor Kinase 2 (β-Adrenergic Receptor Kinase 1) A BINDING PARTNER OF Gβγ SUBUNITS

The solution structure of an extended pleckstrin homology (PH) domain from the β-adrenergic receptor kinase is obtained by high resolution NMR. The structure establishes that the β-adrenergic receptor kinase extended PH domain has the same fold and topology as other PH domains, and there are several unique features, most notably an extended C-terminal α-helix that behaves as a molten helix, and a surface charge polarity that is extensively modified by positive residues in the extended α-helix and the C terminus. These observations complement biochemical evidence that the C-terminal portion of this PH domain participates in protein-protein interactions with Gβγ subunits. This suggests that the C-terminal segment of the PH domain may function to mediate protein-protein interactions with the targets of PH domains.