Localization of a phosphatidylglycerol/ phosphatidylinositol transfer protein in Aspergillus oryzae

The subcellular localization of the phosphatidylglycerol/phosphatidylinosit ol transfer protein (PG/PI-TP) of Aspergillus oryzae was investigated using Western blot analysis of the cell protein extracts, a cellular membrane fr actionation technique, and transmission electron microscopy. The PG/PI-TP, as detected by Western blot analysis with a specific immune serum, was foun d to be mainly cytoplasmic and partly associated with intracellular membran es. A fractionation experiment was conducted after homogenization of the fi lamentous fungus mycelium. The endoplasmic reticulum, Golgi-like vesicles, and the plasma membrane were separated by isopycnic ultracentrifugation on a sucrose gradient, and our data revealed that the immunodetected PG/PI-TP was only associated with the Golgi-like apparatus. All these results were d ocumented by electron microscopy and indicate here for the first time that there exists a specific phospholipid transfer protein in a filamentous fung us that is localized in the cytoplasm and associated with Golgi-like vesicl es.