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A full‐length cDNA encoding Neurospora crassacalmodulin was isolated from λZAP II cDNA expression library. The open reading frame encodes a protein of 148 amino acid residues with a calculated Mr, of 16,865 Da. Using site‐directed mutagenesis, the complete cDNA was ligated into a trcpromoter‐regulated bacterial expression vector to allow expression of N. crassa calmodulin in E. coli. The expressed protein was found to be identical to the native protein on the basis of some of its biochemical properties. Finally, Southern analysis of restriction digests of genomic DNA indicates that calmodulin is encoded by a single‐copy gene.

A calcium, calmodulin-dependent protein kinase activity has been partially purified by calmodulin-Sepharose affinity chromatography from the soluble fraction of Neurospora crassa. The phosphorylated peptide has an apparent molecular mass on SDS-polyacrylamide gel of 47 kDa. The apparent half maximal phosphorylation is obtained after 1.5 min at 30° C in the presence of calcium and calmodulin. The apparent half maximal activation of the phosphorylation is obtained at 1 μM calcium, and 0.1 or 0.2 μM calmodulin from bovine brain or Neurospora, respectively. The 32P incorporation is enhanced about 10-fold by calmodulin.