FIGURE 4.

Ca²⁺ and calmodulin requirements of myristoylation-defective calcineurin. A, site-directed mutagenesis of wild type Cnb1 and Cnb1-G2A was conducted to mutate the first or second EF hand Ca²⁺ binding domain as indicated. Plasmids expressing either wild type or mutant Cnb1 were transformed into cnb1Δ yeast harboring the CDRE-lacZ reporter gene. Quantitative β-galactosidase assays were conducted on yeast grown in YPD (pH 5.5) in the absence of added extracellular CaCl₂ to measure basal CDRE-lacZ activity. B, Cnb1 or Cnb1-G2A expression plasmids were transformed into cmd1–3 cnb1Δ yeast harboring the CDRE-lacZ reporter gene. CDRE-lacZ activity was measured after 4 h of growth in YPD (pH 5.5) in the presence or absence of 100 mm CaCl₂. Data plotted are average of quadruplicates ± S.D.