ISOLATION, CHARACTERIZATION AND EXPRESSION OF A CDNA FOR PEA CHOLINEPHOSPHATE CYTIDYLYLTRANSFERASE

In plants, phosphatidylcholine is the major phospholipid in extra-plas tid membranes and is synthesised mainly by the CDP-choline pathway. Ev idence from studies in animals, as well as in plants, suggests that th e intermediate step catalysed by cholinephosphate cytidylyltransferase (CPCT) has a major control in carbon flux to this lipid. We have isol ated a full-length CPCT cDNA (designated PCT2) from Pisum sativum cv. Feltham First using an Arabidopsis probe and the polymerase chain reac tion (PCR). The deduced amino acid of PCT2 is 48%, 43% and 76% identic al to the rat, yeast and Brassica napus amino acid sequences, respecti vely. Expression of the CPCT protein in Escherichia coli confirmed the activity of the enzyme. Expression of the PCT2 mRNA in pea roots and stems was increased by treatment with 0.1 mu M indole-3-acetic acid.