Intracellular distribution of a 32-KDa calcium-dependent phospholipid-binding protein from human placenta

A 32-KDa calcium dependent phospholipid-binding protein was purified to homogeneity from human placenta by affinity adsorption to polyacrylamide-immobilized phosphatidylserine followed by elution with 5 mM EGTA and ion exchange chromatography. Immunochemical studies using the polyclonal antibody against the 32-KDa protein revealed that this protein was present around the nucleus in the cytoplasm but not clearly associated with cell organelles and cytoskeletons. In KB cells treated with insulin, 32-KDa protein was localized in the ruffling membranes in addition to the cytoplasm. Purified 32-KDa protein was shown to coprecipitate with skeletal muscle actin under polymerizing conditions. These findings suggest that the 32-KDa protein interacts with networks of actin filaments in cells.