ABSTRACT
Phospholipase C (PLC) ß 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 PLCß isozymes and their C-terminal (CT) domains. Strikingly, we found isoforms PLCß1 and PLCß4 to be enriched at the plasma membrane, contrary to isoforms PLCß2 and PLCß3. 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 Gαq-CTßx interactions. By the use of recently developed tools, which enable the on-demand activation of Gαq, we could show that the interaction between constitutively active Gαq and PLCß3 prolongs the residence time of PLCß3 at the plasma membrane. These findings suggest that under physiological circumstances, PLCß3 and Gαq interact in a kiss-and-run fashion, likely due to the GTPase-activating activity of PLCß towards Gαq.
