Fig. 7: PLCβ2 and β3, but not PLCβ1 and β4, use an additional Gs-dependent, cAMP-independent Ca²⁺ release pathway.

HEK-∆_fPLCβ1–4 cells transiently transfected with either empty expression vector (a) or plasmid cDNA coding for each individual PLCβ1–4 isoform (b–e) were primed with solvent or 100 µM ATP (first addition at t = 20 s) followed by a second addition at t = 140 s of Iso or Fsk as indicated. Solvent-primed representative Ca²⁺-fluorescence recordings are buffer-corrected, while Gq-primed exemplary Ca²⁺ fluorescence traces are not. Ca²⁺ responses are quantified as concentration-effect curves for net mean peak responses to Iso, or as bar charts for Fsk and calcium ionophore A23187. Inflection points are marked with the corresponding EC₅₀ values. Representative traces are presented as mean values + SEM, averaged data are mean values ± SEM of n biological replicates (a–c, e: n = 4; d: n = 6), each performed in duplicates. Data in e were fit to a biphasic concentration-effect model to minimize the distance of the measured data points from the predicted data points. Slope factors nH₁ and nH₂ were constrained to equal 2.0 and 1.3 (r² = 0.97) respectively. Statistical significance was calculated with a two-way ANOVA with Šídák’s post-hoc analysis. Source data are provided as a Source Data file.