| Abstract: | The activities of Na,K-, Ca,Mg- and Mg-ATPases in the membrane fractions of plasma membranes of intestinal enterocytes of cattle, brush border and basolateral membranes, were studied. The activities were estimated under conditions of alkaline phosphatase activity inhibition by theophylline to exclude the nonspecific hydrolysis of ATP as well as to establish the orientation of vesicles with the use of alamethicine. 98% of the Na,K-ATPase activity (0.99 +/- 0.031 mumol/mg protein/min) was found to be localized in basolateral membranes. Both the brush border and basolateral membranes were found to possess the Ca,Mg-ATPase (0.193 +/- 0.018 and 0.795 +/- 0.025 mumol/mg protein/min) and Mg-ATPase (0.22 +/- 0.013 and 0.403 +/- 0.022 mumol.mg protein/min) activities. |
