Asymmetric distribution of plasma membrane proteins in mouse L-929 cells.
The distribution of plasma membrane-associated proteins was studied by using latex-filled phagolysosomes prepared from cultured mouse L-929 cells as a model of "inside-out" membrane. Proteins from 131I/lactoperoxidase-labeled phagolysosomes, phagolysosomes derived from 131I/lactoperoxidase-labeled cells, and phagolysosomes prepared from [35S]methionine metabolically labeled cells were analyzed by high-resolution two-dimensional gel electrophoresis. The gel patterns of iodinated proteins showed specific differences in the availability of membrane proteins to lactoperoxidase labeling between inside-out and right-side-out membranes. However, at least two prominent [35S]methionine-labeled proteins of approximately 60,000 and 100,000 daltons were available for iodination at both sides of the membrane. Partial proteolysis of the 100,000-dalton protein revealed that different peptides were iodinated when the iodination was performed on intact cells or on phagolysosomes, consisent with the idea that this protein spans the plasma membrane.
D000818:Animals; D002462:Cell Membrane / Q000648:ultrastructure*; D007739:L Cells; D007784:Lactoperoxidase / Q000378:metabolism; D008247:Lysosomes / Q000648:ultrastructure; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008970:Molecular Weight; D010446:Peptide Fragments / Q000032:analysis; D010587:Phagocytosis
D008565:Membrane Proteins; D010446:Peptide Fragments; D007784:Lactoperoxidase