Abstract
The activity of adenosine triphosphatases in L1210 lymphoid leukemic cells was demonstrated by ultracytochemical methods. The activity of Na+, K+-ATPase was found only in the plasma membrane, but the activity of Mg2+-ATPase and Ca2+-ATPase was found in both the plasma membrane and in the membrane surrounding lipid vacuoles in the cytoplasm. The activity of Ca2+-ATPase predominated on the periphery of the lipid vacuoles. The localization of these enzymes is discussed in reference to its possible significance in transformed cells.
