PREPARATION AND CHARACTERIZATION OF FLUORESCEIN-LABELED PLASMA-MEMBRANE VESICLES FROM TRANSFECTED CHINESE-HAMSTER OVARY CELLS

Plasma membrane vesicles have been used to study a wide variety of bio logical events including the nature of receptor-ligand interactions an d the physiology of molecular transport across membranes. Plasma membr ane vesicles were chemically induced from an adherent Chinese hamster ovary cell line expressing recombinant glycophorin A, a well-studied i ntrinsic membrane protein of the red blood cell. They were also prepar ed from Chinese hamster ovary cells in suspension culture. Biochemical and immunological assays demonstrated the equivalence of glycophorin A on cell membranes and vesicles. The transfected Chinese hamster ovar y cell membrane was also labeled with a highly aliphatic fluorescent c ell linker. Vesicles produced by the fluorescein-labeled cells demonst rated bright surface staining of the plasma membrane. They too express ed glycophorin A biochemically and immunologically indistinguishable f rom cellular-based glycophorin A. Plasma membrane vesicles are non-adh erent in culture and stably retain the fluorescent probe in the cell m embrane. Fluorescein-labeled vesicles will be particularly useful for studying cellular interactions in which both constituents of a recepto r-ligand pair are expressed on adherent cell lines. Unlabeled vesicles may also prove to be useful as soluble immunoadsorbants in both the c linical laboratory and basic science research settings.