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. 2012 Feb 22;287(15):11981–11990. doi: 10.1074/jbc.M111.338525

FIGURE 5.

FIGURE 5.

PH domain of SCAB1 binds inositol phosphates via a low-affinity surface site. A, ITC of SCAB1(272–496) with inositol phosphates Ins(1,4,5)P3, Ins(1,2,3,4,5,6)P6, and Ins(1)P. The curves in the lower panels are the best fit to a one-set-of-sites binding model. The derived dissociation constants (Kd) are indicated. B, ITC of the SCAB1(272–496) mutants R410N, K412N, and K422N with Ins(1,4,5)P3. C, electrostatic potential surface for the PH domain. The surface is colored in blue to red for positively to negatively charged regions. The arrow points to the equivalent high-affinity inositol phosphate (IP)-binding pocket, which is not negatively charged in SCAB1. D, interaction between the SCAB1 PH domain and malonate. The dotted lines denote hydrogen bonds. E, structure of the phospholipase Cδ1 (PLC-δ) PH domain in complex with Ins(1,4,5)P3 (Protein Data Bank code 1MAI) aligned with the SCAB1 PH domain structure. F, structure of the β-spectrin PH domain in complex with Ins(1,4,5)P3 (Protein Data Bank code 1BTN) aligned with the SCAB1 PH domain structure.