Molecular cloning and characterization of the Arabidopsis thaliana alpha-subunit of elongation factor 1B

Using a PCR-based approach,,ve have isolated two Arabidopsis thaliana cDNA clones (alpha 1 and alpha 2) encoding the alpha-subunit of translation elon gation factor 1B (eEF1B alpha). They encode open reading frames of 228 and 224 amino acids respectively, with extensive homology to eEF1B alpha subuni ts from different organisms, particularly in the C-terminal half of the pro tein, They both lack a conserved phosphorylation site that has been implica ted in regulating nucleotide exchange activity, Using a plasmid shuffling e xperiment, me demonstrated that both al and alpha 2 clones are able to comp lement a mutant yeast strain deficient for the eEF1Ba subunit, This provide s evidence that Arabidopsis encodes at least two functional isoforms of thi s subunit, termed eEF1B alpha 1 and eEF1B alpha 2. A third cDNA clone was i solated that appeared to result from an alternative splicing event of the e EF1B alpha 1 gene. (C) 1999 Federation of European Biochemical Societies.