5 NEW 14-3-3-ISOFORMS FROM NICOTIANA-TABACUM-L - IMPLICATIONS FOR THEPHYLOGENY OF PLANT 14-3-3-PROTEINS

About thirty years after the initial identification of 14-3-3 proteins in mammalian brain, they are now thought to be ubiquitous among eukar yotes. We identified five cDNAs encoding 14-3-3 proteins of Nicotiana tabacum L. using a polymerase chain reaction (PCR)-based screening str ategy. A phylogenetic analysis was carried out with 14-3-3 amino-acid sequences from twelve plant species. The results showed that 14-3-3 pr oteins of plants can be divided into at least five different subgroups . Four of these subgroups resulted from early gene duplication events that happened prior to the speciation of most of the plant species con sidered. Interestingly, 14-3-3 epsilon isoforms from mammals and insec ts form one subgroup together with epsilon-like isoforms from plants. The 14-3-3 genes known from monocots descend from the same ancestor, f orming the fifth subgroup.