Catalyzes the transfer of phosphatidylinositol (PI) between membranes (PubMed:10531358, PubMed:22822086). Binds PI, phosphatidylcholine (PC) and phosphatidic acid (PA) with the binding affinity order of PI > PA > PC (PubMed:22822086). Regulates RHOA activity, and plays a role in cytoskeleton remodeling (PubMed:11909959). Necessary for normal completion of cytokinesis (PubMed:15125835). Plays a role in maintaining normal diacylglycerol levels in the Golgi apparatus (PubMed:15723057). Necessary for maintaining the normal structure of the endoplasmic reticulum and the Golgi apparatus (PubMed:15545272). Required for protein export from the endoplasmic reticulum and the Golgi (PubMed:15723057). Binds calcium ions (PubMed:10022914).