PROTEIN PHOSPHATASES AND PROTEIN-KINASES IN HIGHER-PLANTS

The recent gain in knowledge concerning enzymes involved in signal tra nsduction pathways is a direct consequence of the considerable advance s made in molecular biology. Protein kinases and protein phosphatases, the two major enzymes implicated in post-translational modifications, have been studied in particular. The number of characterized plant ge nes and/or cDNAs encoding these enzymes is increasing everyday. Since 1991, 26 genes and cDNAs coding for plant protein phosphatases have be en isolated and characterized. The huge number of protein kinases (est imated at several thousands) makes it impossible to give an exhaustive list of the genes already identified, but a classification of these e nzymes, based on phylogenetic criteria, allows us to appreciate the ra nge of functions this protein family may play in plants.