Abstract

Calmodulin-binding protein-10 (CaMBP10) was isolated previously from Chinese cabbage and identified as a member of the lipid transfer protein family. In this study, we found that CaMBP10 was phosphorylated in a calcium( Ca2+)-dependent manner, and the phosphorylation was inhibited by calmodulin (CaM) antagonists. In-gel kinase assay revealed that the phosphorylation of CaMBP10 was catalyzed by a 45 kDa protein kinase, which underwent autophosphorylation in the presence of Ca2+. Immunoblotting assay further identified this kinase as a calcium-dependent protein kinase (CDPK). In addition, the phosphorylation site was mapped to the C-terminal region of CaMBP10, where the CaMbinding domain resides. These results provide novel insights into the molecular mechanisms that regulate CaMBP10 functions.

Keywords: Calcium-dependent protein kinase, calmodulin-binding protein-10, calmodulin, lipid transfer protein, phosphorylation, Calmodulin-binding protein-10 (CaMBP10), calmodulin (CaM) antagonists, C-terminal region, Lipid transfer proteins (LTPs), anti-CDPK antibody, Chinese cabbage, CaM-gel, 2-mercaptoethanol, SDS-PAGE, In-Gel Kinase Assay, Immunoblotting Analysis, Site-Directed Mutagenesis, Lipid-Binding Activity, exogenous CaMBP10, CDPK Phosphorylation Site, CaM-binding domains, Dithiothreitol, Phenylmethylsulfonyl, N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamideCalcium-dependent protein kinase, calmodulin-binding protein-10, calmodulin, lipid transfer protein, phosphorylation, Calmodulin-binding protein-10 (CaMBP10), calmodulin (CaM) antagonists, C-terminal region, Lipid transfer proteins (LTPs), anti-CDPK antibody, Chinese cabbage, CaM-gel, 2-mercaptoethanol, SDS-PAGE, In-Gel Kinase Assay, Immunoblotting Analysis, Site-Directed Mutagenesis, Lipid-Binding Activity, exogenous CaMBP10, CDPK Phosphorylation Site, CaM-binding domains, Dithiothreitol, Phenylmethylsulfonyl, N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide