The Calcium-Dependent Interaction of S100B with Its Protein Targets

Figure 6

Characterization of CaM-488 target protein binding. Equimolar concentrations of CaM kinase II (CKII) phosphorylase kinase (PK) were immobilized on a PVDF membrane and incubated with 100 nM CaM-488 in the presence of Ca²⁺ or EDTA. Panel A contains a representative dot blot image. The histograms in Panel B represent the mean pmoles CaM-488 bound in the presence (black bars) and absence (gray bars) of Ca²⁺ assayed in triplicate in two independent experiments. Consistent with reported K_ds and K_as, both targets exhibited Ca²⁺-dependent binding with the higher affinity target, CKII, binding more CaM-488 (7.0 pmoles) when compared to the lower affinity target PK (0.8 pmoles).

(a)

(b)