Characterisation and cloning of a calmodulin-like domain protein kinase from Chlamydomonas moewusii (Gerloff)

Calcium-stimulated protein kinase activity in the flagella of the green alga Chamydomonas moewusii (Gerloff) was characterised. Using SDS-PAGE and an on-blot phosphorylation assay, a 65-kDa protein was identified as the major calcium-stimulated protein kinase, Its activity was directly stimulated by calcium, a characteristic of the calmodulin-like domain protein kinases (CDPKs). Monoclonal antibodies raised against the CDPK alpha from soybean cross-reacted with the 65-kDa protein in the flagella, and also with other proteins in the flagellum and cell body. The same monoclonal antibodies were used to screen a C. moewusii cDNA expression library in order to isolate CDPK cDNAs from C. moewusii. The CCK1 cDNA encodes a protein with a kinase and calmodulin-like domain linked by a junction domain typical of CDPKs. From Southern analyses, evidence was obtained for a CDPK gene family in C. moewusii and C. reinhardtii.