Heterogeneity of Acid Phosphatase in the Human Diploid Cell Strain WI-38.

A subcellular fraction has been prepared from human diploid cell strain WI-38 which has the characteristics of lysosomes: this fraction contains the greatest percentage of acid phosphatase activity and in terms of specific activity is enriched over the whole homogenate. The activity is sedimentable and membrane-bound and, once released by a detergent, is no longer sedimentable. In addition, we have shown that two forms of acid phosphatase exist in WI-38 cells based on differences in subcellular localization, pH optimum, sensitivity to inhibitors, thermal stability and electrophoretic mobility.