Almost all of the proteins found in skeletal muscle extracts, including the Ca ²⁺ +Mg ²⁺ -ATPase and the 53,000-Da glycoprotein of the sarcoplasmic reticulum, are stained red or pink with Stains-all. Calsequestrin, the 1 60,000-Da glycoprotein, and 170,000-Da protein are stained blue with Stains-all. The ratio of Stains-all staining (measured at 615 nm) to that of Coomassie blue staining (measured at 575 nm) is 1.3 for calsequestrin, 2.0 for calmodulin, 1.4 for troponin C, and 2.2 for S-100. Therefore, in addition to differentially staining these Ca ²⁺ -binding proteins blue, Stains-all is a more sensitive stain for these Ca ²⁺ -binding proteins than is Coomassie blue.