Structure of PKBαPH complexed to Ins(1,3,4,5)P4. A ribbon structure of the PH domain of PKBα, depicting the localization of Thr34 relative to that of Arg25 and Arg23, which play a critical role in the binding of the inositol head group, is shown. Also labeled are the seven β strands (labeled β1 to β7). The ribbon drawing is based on the crystal structure proposed by Thomas et al. (47).