Cloning and expression analysis of the wheat gene TaRop2 encoding a small GTP-binding protein Research Progress on Rab Proteins in Plants Cloning and expression analyses of the wheat gene TaRop3 encoding a small GTP-binding protein Characterization and Functional Analysis of a Small GTP-binding Protein AtRAB Interacting with H+-Pyrophosphatase AVP1 in Arabidopsis thaliana