Lipid-poor apolipoprotein A-I in Hep G2 cells formation of lipid-rich particles by incubation with dimyristoylphosphatidylcholine》.pdfVIP

Biochimica et Biophysics Acta 920 (1987) 185-194 185 Elsevier BBA 52574 Lipid-poor apolipoprotein A-I in Hep G2 cells: formation of lipid-rich particles by incubation with dimyristoylphosphatidylcholine Trudy M. Forte a, Alex V. Nichols a, Janet Selmek-Halsey a, Lisa Caylor a and Virgie G. Shore b a Donner Loboratory Lawrence Berkeley Laboratory, University of California, Berkeley, and b Lawrence Livermore National Laboratory, University of California, Livermore, CA (U.S.A.) (Received 9 February 1987) Key words: Apolipoprotein A-I; Dimyristoylphosphatidylcholine; Electron microscopy; Gradient gel electrophoresis; Proapolipoprotein; (Hep G2 cells) Apolipoprotein A-I is a major secretory product of the human hepatoma cell line, Hep G2; approx. 70% of apolipoprotein A-I was separated from the medium as lipid-poor apolipoprotein A-I in the d 1.21 g/ml fraction while 30% was associated with high-density lipoproteins (HDL) of d 1.063-1.21 g/ml. The lipid-poor apolipoprotein A-I contains 50% proapolipoproteinA-I which is similar to the isoform distribution in Hep G2 preformed HDL. We tested the ability of lipid-poor apolipoprotein A-I from Hep G2 to form complexes with dimyristoylphosphatidylcholine (DMPC) vesicles at DMPC/apolipoprotein A-I molar ratios of 100: 1 and 300: 1. Lipid-poor apolipoprotein A-I formed complexes which floated at d