Abstract
CHUP1 protein is essential for chloroplasts to take proper positioning according to light condition. CHUP1 protein contains multiple functional domains, such as 25 amino acid sequence at N-terminus targeting to the chloroplast outer envelop membrane, F-actin binding motif, and prolin-rich region (Oikawa et al, 2003). CHUP1 localization was studied using polyclonal antibody against CHUP1. The result suggests that the hydrophobic sequence at the N-terminus of CHUP1 is important for CHUP1 localization. Next, we studied the relationship between CHUP1 functional domains and recovery of light induced chloroplast relocation in chup1 using constructs defective in each functional domain of the CHUP1 protein. Results showed that CHUP11-500aa could partially recover the mutant phenotype of chup1 and the chloroplast positioning was similar to positioning under strong light even under weak light condition, and that C-terminus of CHUP1 is important for chloroplasts to take proper intracellular positioning and may function for G-actin polymerization.
