Isolation of Plasma Membrane Fragments From Bhk21 Cells

We have isolated fractions rich in plasma membranes from baby hamster kidney cells (BHK21) by using a modification of the method of Wallach & Kamat (1966). The specific activity of Na+‐K+‐activated ATPase was 10–20 fold higher in the plasma membranes than in the original homogenate. Antiserum against whole cells gave a strong plasma membrane fluorescence and agglutinated intact BHK21 cells. Quantitative agglutination inhibition studies indicated a 20 fold concentration of the plasma membrane antigens in the isolated plasma membrane fraction. In isolated plasma membrane fractions NADH‐ diaphorase activity was low and succinate dehydrogenase activity not detectable.