Sustained agonist-induced production of the second messengers InsP3 and diacylglycerol requires steady delivery of phosphatidylinositol (PtdIns) from its site of synthesis in the ER to the plasma membrane (PM) to maintain PtdIns(4,5)P2 levels. Similarly, phosphatidic acid (PtdOH), generated from diacylglycerol in the PM, has to reach the ER for PtdIns resynthesis. Here, we show that the Drosophila RdgB homolog, Nir2, a presumed PtdIns transfer protein, not only transfers PtdIns from the ER to the PM but also transfers PtdOH to the opposite direction at ER-PM contact sites. PtdOH delivery to the ER is impaired in Nir2-depleted cells, leading to limited PtdIns synthesis and ultimately to loss of signaling from phospholipase C-coupled receptors. These studies reveal a unique feature of Nir2, namely its ability to serve as a highly localized lipid exchanger that ensures that PtdIns synthesis is matched with PtdIns(4,5)P2 utilization so that cells maintain their signaling competence. Display omitted •Nir2 protein supports phosphatidic acid transfer from the plasma membrane (PM) to the ER•Nir2 translocates to ER-PM contact sites during PLC activation•Nir2 delivers phosphatidic acid to the ER for PtdIns synthesis•Accelerated phosphoinositide turnover is confined to ER-PM contact zones Kim et al. identify the Nir2 protein as a lipid transporter that moves phosphatidylinositol from the ER to the plasma membrane while transferring phosphatidic acid in the other direction. Therefore, Nir2 helps maintain plasma membrane lipid identity when phosphoinositides are rapidly consumed during receptor-mediated activation of phospholipase C enzymes.