Radioiodination of L 1210 cells

The lymphoid leukaemia L 1210 cells of mice were labelled with 125I. The cell homogenates were fractionated and from the microsomal fraction 90 per cent of the radioactive material could be precipitated with perchloric acid, whereas only 4 per cent was precipitated from the soluble fraction. Papain bound with Enzacryl AH released 31 per cent of radioactivity. It was concluded therefrom that the surface proteins of the cells were labelled. Electrophoretic separation of these proteins in polyacrylamide gel with sodium dodecyl sulphate was performed and 6--8 radioactive fractions of surface peptides were found.