Figure 3.

Binding and inhibition of calcineurin in vitro by Rcn1p, DSCR1, and DS-24 peptide. (A) GST, GST–Rcn1p, and GST–DSCR1 were immobilized on glutathione-sepharose beads and assayed for the ability to bind purified bovine brain calcineurin. (B) Immobilized GST–DSCR1, but not GST alone bound calcineurin in buffer A, or buffer A supplemented with either 2 mm CaCl₂ or 2 mm EGTA. (C) GST–DSCR1/calcineurin bound to FK506/FKBP12 in the presence of calmodulin and 2 mm CaCl₂. (D–F) Dephosphorylation of RII peptide by calcineurin was inhibited by purified GST–DSCR1, GST–Rcn1p (100 μg/ml), and DS-24 synthetic peptide. Ten-fold excess calmodulin failed to reverse calcineurin inhibition by DSCR1.