Binary/ternary binding affinity, cooperativity, and ternary
complex
formation of XL01126, XL01134, and SD75. (A). Schematic illustration
of the binary and ternary LRRK2 engagement assays. HG-10-102-01, XL01126
(B), XL01134 (C), and SD75 (D) were titrated into the lysate of HEK293
cells (transfected LRRK2-NanoLuc) alone (blue line) or preincubated
with VCB (red line) in the presence of LRRK2 tracer. The fractional
occupancy of the tracer is plotted against the concentrations of the
compounds and fitted into the “nonlinear regression, one site-log IC50” model in GraphPad to obtain the IC50 values.
The IC50 ratio between the blue curve and red cure is calculated
as cooperativity (α). (E) Schematic illustration of the ternary
complex formation assay (F). cis-XL01126, XL01126,
SD75, and XL01134 were titrated into the lysate of HEK293 cells (transfected
with LRRK2-NanoLuc) and 0.5 μM VCB protein labeled with Bodipy576/589. The NanoBRET signal was plotted against the compounds’
concentrations and fitted into “nonlinear regression, Gaussian”
model in GraphPad. Error bars are mean ± SEM from three biological
independent experiments.