PLCβ isoforms differ in their subcellular location and their CT-domain dependent interaction with Gαq

Phospholipase C (PLC) beta isoforms are implicated in various physiological processes and pathologies. However, mechanistic insight into the localization and activation of each of the isoforms is limited. Therefore, it is crucial to gain more in-depth knowledge as to the regulation of the different isoforms. Here we describe the subcellular location of full-length PLC beta isozymes and their C-terminal (CT) domains. Strikingly, we found isoforms PLC beta 1 and PLC beta 4 to be enriched at the plasma membrane, contrary to isoforms PLC beta 2 and PLC beta 3. We determined that the CT domain is an inhibitor of Gq-mediated increases in intracellular calcium, the potency of its effect being dependent upon the CT domain isoform used. Furthermore, ratiometric fluorescence resonance energy transfer (FRET) imaging was used to study the kinetics of the G alpha q-CT beta x interactions. By the use of recently developed tools, which enable the on-demand activation of G alpha q, we could show that the interaction between constitutively active G alpha q and PLC beta 3 prolongs the residence time of PLC beta 3 at the plasma membrane. These findings suggest that under physiological circumstances. PLC beta 3 and G alpha q interact in a kiss-and-run fashion, likely due to the GTPase-activating activity of PLC beta towards G alpha q. (C) 2012 Elsevier Inc. All rights reserved.