The demonstration of a specific 5'-nucleotidase activity in rat tissues.

5′-Nucleotidase has been partially purified from rat liver, spleen, kidney, heart, lung, brain and skeletal muscle. The majority of the enzyme activity in each of these tissues was insoluble in 1% of Triton X-100, solubilized in 2% Triton X-100,1% sodium deoxycholate, and stable to incubation at 50 °C for 5 min. The partially purified enzyme from each tissue exhibited the same pH optimum, was inhibited by concanavalin A, and was inhibited in an identical manner by antibody to highly purified 5′-nucleotidase from liver. Since the enzyme is usually concentrated in the plasma membrane (De Pierre, J. W. and Karnovsky, M. L. (1973) J. Cell Biol., 56, 275–303), the results indicate that the enzyme may represent a convenient and general marker for this organelle in rat tissues.