A Calcium-dependent Protein Kinase (CDPK) in the Unicellular Green Alga Closterium ehrenbergii

Abstract

An in-gel kinase assay revealed that homogenates of Closterium ehrenbergii contain Ca 2+ -dependent protein kinases (CDPKs) ranging in relative molecular mass from 47 to 60 kDa, that phosphorylated histone H1, myelin basic protein, and casein as substrates in a Ca 2+ -dependent manner. Immunoblotting and immunoprecipitation assays of Closterium extracts using anti-Dunaliella CDPK serum showed that the antibody cross-reacted with a Closterium CDPK with a relative molecular mass of 55 kDa in the soluble fraction. These results indicate that Closterium possesses CDPK-related polypeptides: one is a 55-kDa CDPK that is immunologically related to Dunaliella CDPK and the others have various molecular masses.

Two Calcium-Dependent Protein Kinases fromChlamydomonas reinhardtiiare transcriptionally regulated by nutrient starvation

“…Of these, the 55 kDa CDPK was found to be immunologically related to the 62 kDa D. tertiolecta CDPK. 49 Another CDPK was found to share epitopes with the 62 kDa D. tertiolecta CDPK that was present in the internodal cells of the brackish water inhabiting Lamprothamnium succinctum charophyte. This enzyme of 53 kDa was found to be involved in processing turgor regulation in response to hypoosmotic treatment.…”

“…Due to this conformational change, a mobility shift is seen in the presence of calcium. 49,[51][52][53][54] The electrophoretic mobility of the CDPK1-GFP fusion protein was compared in the presence and absence (EGTA) of Ca 2+ . As expected, the mobility shift of the fusion protein was clearly seen in presence of Ca 2+ when compared to that treated with EGTA, and a 4 kDa difference was observed (Fig.…”