The function and subcellular localization of an Arabidopsis 14-3-3 protein, GF14 lambda

The 14-3-3 proteins play important roles in signal transduction pathways and regulating cellular enzyme activities in eukaryotes. GF14lambda, one of the fourteen 14-3-3 protein isoforms found in Arabidopsis, interacts with several proteins, including AKR2 (ankyrin repeat-containing protein 2) and APX3 (ascorbate peroxidase 3) proteins. AKR2 may function as a regulatory protein of APX3, because it interacts with APX3 specifically and protects APX3's activity in vitro. The APX3 protein is involved in hydrogen peroxide-scavenging in peroxisomal membranes. These protein-protein interactions may be involved in a novel antioxidation regulation mechanism in higher plants. The GF14lambda protein may serve as a scaffold protein in this mechanism. GF14lambda was localized to the nucleus and cytoplasm by fusing it to GFP (green fluorescent protein) and studying their localization using fluorescence microscopy and immunoelectron microscopy. Furthermore, the function of GF14lambda was studied in anti-GF14lambda transgenic plants. Our data indicate that GF14lambda plays an important role in plant cold tolerance, because reduced expression of GF14lambda leads to sensitive phenotypes under chilling temperature conditions. The implication of our discovery with respect to the general functions of 14-3-3 proteins in eukaryotes is discussed in this dissertation.