CLONING AND EXPRESSION ANALYSIS OF MURINE PHOSPHOLIPASE D1

Activation of phosphatidylcholine-specific phospholipase D (PLD) occur s as part of the complex signal-transduction cascade initiated by agon ist stimulation of tyrosine kinase and G-protein-coupled receptors. A variety of mammalian PLD activities have been described, and cDNAs for two PLDs recently reported (human PLD 1 and murine PLD2). We describe here the cloning and chromosomal localization of murine PLD1. Norther n-blot hybridization and RNase protection analyses were used to examin e the expression of murine PLD1 and PLD2 in a variety of cell lines an d tissues. PLD1 and PLD2 were expressed in all RNA samples examined, a lthough the absolute expression of each isoform varied, as well as the ratio of PLD1 to PLD2. Moreover, in situ hybridization of adult brain and murine embryo sections revealed high levels of expression of indi vidual PLDs in some cell types and no detectable expression in others. Thus the two PLDs probably carry out distinct roles in restricted sub sets of cells rather than ubiquitous roles in all cells.