The pleckstrin homology domain of phospholipase C-β₂ links the binding of Gβγ to activation of the catalytic core

Pleckstrin homology (PH) domains are membrane tethering devices found in many signal transducing proteins. These domains also couple to the βγ subunits of GTP binding proteins (G proteins), but whether this association transmits allosteric information to the catalytic core is unclear. To address this question, we constructed protein chimeras in which the PH domain of phospholipase C-β₂ (PLC-β₂), which is regulated by Gβγ, replaces the PH domain of PLC-δ₁ which binds to, but is not regulated by, Gβγ. We found that attachment of the PH domain of PLC-β₂ onto PLC-δ₁ not only causes the membrane-binding properties of PLC-δ₁ to become similar to those of PLC-β₂, but also results in a Gβγ-regulated enzyme. Thus, PH domains are more than simple tethering devices and mediate regulatory signals to the host protein.