Plants Prenylation Modification Of Functional Protein Research

Calmodulin (CaM) is a small heat-stable Ca2+-bindinding protein highly conserved in eukaryotes. An unusual rice calmodulin isoform, OsCaM61, was first obtained in our lab, which contains an N-terminal CaM domain and a C-terminal basic extension with a potential prenylation site. In vitro activity assays confirm OsCaM61 as a functional calmodulin. Using the green fluorescent protein (GFP) as a visual marker, we further studied subcellular localization of OsCaM61 in stably transformed tobacco cells. The GFP- OsCaM61 fusion protein was membrane-associated whereas OsCaM61-GFP was mainly detected in the nucleoplasm. GFP- OsCaM61 was transported into the nucleoplasm upon a block in isoprenoid biosynthesis by mevinolin treatment of tobacco cells. These results indicate that the prenylated OsCaM61 molecules are mainly membrane-associated while its unprenylated counterparts are transported into the nucleoplasm. Thus, OsCaM61 may play functions in coordinating Ca2+ signaling with isoprenoid metabolism.