PLASMA MEMBRANE OF A MURINE T CELL LYMPHOMA: SURFACE LABELLING, MEMBRANE ISOLATION, SEPARATION OF MEMBRANE PROTEINS AND DISTRIBUTION OF SURFACE LABEL AMONGST THESE PROTEINS

Abstract

Two established techniques for analysis of plasma membranes, namely. Iactoperoxidase catalyzed surface radioiodination of intact cells and bulk membrane isolation following disruption of cells by shear forces, were applied in studies of membrane proteins of continuously cultured cells of the monoclonal T lymphoma line WEHI-22. It was found that macromolecular ¹²⁵I-iodide incorporated into plasma membrane proteins of intact cells was at least as good a marker for the plasma as was the commonly used enzyme 5'-nucleotidase. T lymphoma plasma membrane proteins were complex when analysed by polyacrylamide gel electrophoresis in sodium dodecylsulphate-cotaining buffers and more than thirty distinct components were resolved. More than fifteen of the components observed on a mass basis were also labelled with ¹²⁵I-iodide. Certain bands, however, exhibited a degree of label disproportionate to their staining properties with Coomassie Blue. This was interpreted in terms of their accessibility to the solvent in the intact cells.