Abstract：Rab proteins have the conserved cystein residues at C terminus, which are the prenylational modification site after protein translation. In this study, we obtained Arabidopsis RabD2b mutant alleles with either lacking both two conserved cystein residues at 199 and 200 (AtRabD2bΔCC) or altering one conserved cystein residue at 199 to serine residue (AtRabD2bC199S) by site mutation. When the mutated genes were transiently transformed into tobacco(Nicotiana tabacum) leaves or stably transformed into Arabidopsis, it was found that they were both targeted to the cytoplasm, while wild-type AtRabD2b was mainly localized on Golgi stacks. The lethal phenotype at certain temperature of Yeast Ypt1, a temperature-sensitive mutant stain, could be recovered by the transformation of AtRabD2b. However, two mutant AtRabD2b proteins both lost the complementary ability. These results suggested that the mutation of single conserved cystein residue or lacking of the two conserved cystein residues at C terminus affected the localization and function of AtRabD2b. The results provide the reference data for further study on the mechanism of plant Rab prenylational modification.
