Abstract
Recently, we found novel cation-binding proteins in Arabidopsis thaliana. One of these proteins, AtPCaP2 consists of 168 amino acid residues and contains N-myristoylation signal and repetitive unique motifs (VEExK). To estimate its physiological role we characterized molecular properties of AtPCaP2. Quantitative RT-PCR revealed that AtPCaP2 was predominantly expressed in roots. The promoter::GUS expression analysis confirmed the root specific expression. The mRNA level was increased more than three-fold when plantlets were treated with bacterial elicitor peptide, heavy metals such as Fe2+ and Mn2+, low temperature, drought, abscisic acid and osmotic stresses. When a AtPCaP2::GFP fusion protein was expressed in Arabidopsis cells, green fluorescence was clearly observed on the plasma membrane. Further analyses revealed that AtPCaP2 was N-myristoylated at the N-terminal part and has capacity to bind specific phosphatidylinositol phosphates. These properties suggest a possibility that AtPCaP2 is involved in responses to a variety of physiological stresses.
