Molecular cloning and structural analysis of cDNAs that encode 3 small GTP-binding proteins from sugar beet.

Isolation of homologous ras-related genes from sugar beet has never been reported. Screening cDNA library from Beta vulgaris L. Hilma resulted in the isolation of 3 ras-homologous clones. Two of these genes (rab1Bv and rab2Bv) belong to the Rab/Ypt group. The deduced polypeptidic sequences from them show strong homologies to Ara3 (93% with Rab1Bv) of Arabidopsis thaliana and Rgp2 (97% with Rab2Bv) of Oryza sativa. The third gene (rho1Bv) belongs to the Rho family. The homology of Rho1Bv protein with Rho1Ps from Pisum is very high (98%). Rho1Bv is the second representative plant Rho protein described in the literature. The homologies of all these 3 small GTP-binding proteins indicate that these proteins are conserved in plant families like Chenopodiaceae, Brassicaceae, Fabaceae and Poaceae and could control important transductional pathways conserved along the processes of evolution.