Abstract
AtRBP1, an RNA-binding protein found in Arabidopsis thaliana, contains two CS-RBDs and is expressed in actively proliferative regions such as root tips, shoot apexes, and calli. We approached the biological roles of AtRBP1 with two methods. First, we generated the transgenic plants whose expression of AtRBP1 gene is suppressed. These transgenic plants showed stunted root growth and depressed salt tolerance. Then we identified RNA sequences bound to AtRBP1. A binding assay using random 50nt RNAs and AtRBP1 expressed in E. coli revealed that UUAGG sequence and its similar sequence can bind to AtRBP1. In order to identify the target RNAs of AtRBP1 in vivo, we immunoprecipitated RNA-AtRBP1 complexes from cell extract of transgenic plants expressing fusion proteins of EGFP and AtRBP1 using anti-GFP antibody. We synthesized cDNAs from RNAs extracted from the immunoprecipitates. After the cloning of cDNAs, the sequences of them were determined. We found some candidate RNAs, which bind to AtRBP1 in vivo. At present, we continue to isolate other candidate RNAs and identify the authentic target RNAs of AtRBP1.
