Fig. 9.

Coomassie blue-stained polyacrylamide gels showing proteins that bound to calmodulin-Sepharose and Sepharose 4B in the presence of different concentrations of Ca²⁺. Soluble extracts of Limulus lateral eye plus lateral optic nerves were incubated with calmodulin-Sepharose or Sepharose 4B without bound calmodulin in the absence or presence of different concentrations of Ca²⁺ (see Materials and Methods). Proteins that bound to the beads were extracted into SDS sample buffer, fractionated by SDS-PAGE, and stained with Coomassie blue. The positions of the molecular mass standards are indicated.A, In the absence of calcium, myoIII_Lim, the protein band that migrates close to the 116 kDa molecular mass standard (arrows), bound to calmodulin-Sepharose but not to Sepharose 4B. B, MyoIII_Lim bound to calmodulin-Sepharose in the absence of Ca²⁺ and in the presence of 0.1 μmfree Ca²⁺. Binding of myoIII_Lim to calmodulin-Sepharose was reduced in the presence of 1.6 and 17 μm free Ca²⁺, and the binding of other proteins was enhanced. Note in particular the bands that migrate at 57 and 53 kDa.