[5'-Nucleotidase as an "internal probe" in studying steroid hormone interaction with the plasma membranes of target cells].

Changes in the activity of 5'-nucleotidase, the marker enzyme of plasma membranes, in membrane cells of the uterus and liver were examined upon action of tropic and nontropic steroid hormones. In case of tropic steroids, the curves of changes in the activity with rise in the hormone concentration are complicated and broken with a marked minimum at 10(-8) M. Upon the action of nontropic hormones there takes place a monotonous rise in the enzymatic activity. The characteristic differences as shown by the curves make it possible to apply 5'-nucleotidase as endogenous probe during studies into hormone-membrane interactions.