Purification of calmodulin from Chlamydomonas: calmodulin occurs in cell bodies and flagella.

Abstract

Calmodulin was purified from cell bodies of the green alga Chlamydomonas by Ca2+-dependent affinity chromatography on fluphenazine-Sepharose 4B. Calmodulin from this primitive organism closely resembles that from bovine brain in a number of properties, including binding to fluphenazine in a Ca2+-dependent, reversible manner, functioning as a heat-stable, Ca2+-dependent activator of cyclic nucleotide phosphodiesterase, and electrophoretic mobility in sodiumdodecyl sulfate-polyacrylamide gels in both the presence and absence of Ca2+ which causes a shift in the relative mobility of calmodulin. Calmodulin was identified by the criteria of phosphodiesterase activation and electrophoretic mobility in both the detergent soluble membrane plus matrix and the axoneme fractions of Chlamydomonas flagella. Calmodulin is not associated with the partially purified 12S or 18S dynein ATPases of Chlamydomonas. The presence of calmodulin in the flagellum suggests that it is involved in one or more of the Ca2+-dependent activities of this organelle.