Release of Surface-Associated Phosphoesterases from HeLa Cells by Ficin 1

Summary

Two strains of HeLa cells designated as S3G and S3K were treated at 37° with a 0.4% solution of ficin. The treatment resulted in a loss of from 15 to 30% of cellular protein. Four phosphoesterases known † be associated with the plasma membrane, viz., alkaline phosphatase, inorganic pyrophosphatase, (Na⁺, K⁺)-ATPase, and 5′-nucleotidase, were assayed after ficin treatment in the supernatant fluid and in the remaining cell pellets. In most instances, ficin substantially increased the shedding of these enzymes by the cells. Some inhibition of the protein leakage was observed in cells exposed during growth to 0.5 μg/ml of prednisolone. The loss of protein and the shedding of membrane-associated enzymes did not result in a decrease of cell viability as judged by cell cloning and dye exclusion assays.