Apolipoprotein A-I-binding protein from human term placenta. Purification and partial characterization.

A protein that binds to the main apoprotein, apoA-I, of human high density lipoprotein (HDL) has been isolated from human placenta. Ligand blotting after SDS gel electrophoresis indicated that the 120 kDa protein in the absence of reducing agents binds apoA-I. If gel electrophoresis was performed under reducing conditions two main bands, approx. 50 and 30 kDa that did not bind apoA-I, were evident. In an enzyme-linked immunosorbent assay the binding protein specifically bound apoA-I, delipidated or as HDL. ApoA-II, apo E and LDL did not compete with apoA-I for binding to this protein.