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 be en reported Screening cDNA library from Beta vulgaris L. Hilma resulte d in the isolation of 3 ras-homologous clones. Two of these genes (rab 1Bv and rab2Bv) belong to the Rab/Ypt group. The deduced polypeptidic sequences from them show strong homologies to Ara3 (93% with Rab1Bv) o f 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 seco nd representative plant Rho protein described in the literature. The h omologies of all these 3 small GTP-binding proteins indicate that thes e proteins are conserved in plant families like Chenopodiaceae, Brassi caceae, Fabaceae and Poaceae and could control important transductiona l pathways conserved along the processes of evolution.