Figure 3.

PLB reassociation with SERCA after Ca²⁺transients are delayed by slow dissociation from the PLB pentamer.A, schematic diagram of shifts in PLB and DWORF binding equilibria during Ca²⁺ release. B, representative single exponential decay fit of the kinetics of DWORF–SERCA binding during Ca²⁺ release. C, kinetics of PLB–SERCA unbinding during Ca²⁺ release. D, kinetics of PLB–PLB binding during Ca²⁺ release. E, the latency of FRET ratio changes compared to Ca²⁺ release with lines representing mean ± SEM. Differences determined by one-way ANOVA with Dunn’s post hoc test (∗p < 0.05, see Table S4 for complete statistical analysis). F, schematic diagram of shifts PLB and DWORF binding equilibria during Ca²⁺ uptake. G, representative single exponential decay fit of the kinetics of DWORF–SERCA unbinding during Ca²⁺ uptake. H, kinetics of PLB–SERCA rebinding during Ca²⁺ uptake. I, kinetics of PLB–PLB binding during Ca²⁺ release. J, the latency of FRET ratio changes compared to Ca²⁺ release with lines representing mean ± SEM. Differences determined by one-way ANOVA with Dunn’s post hoc test (∗p < 0.05, see Table S7 for complete statistical analysis). DWORF, dwarf ORF; PLB, phospholamban; SERCA, sarco/endoplasmic reticulum Ca²⁺-ATPase.