Ion transport and phosphoproteins of human red blood cells

ULTRACYTOCHEMICAL LOCALIZATION OF OUABAIN-SENSITIVE, POTASSIUM-DEPENDENT <i>P</i>-NITROPHENYLPHOSPHATASE ACTIVITY IN THE GUINEA PIG RETINA

“…His method was to utilize the p-nitrophenylphosphatase activity of the dephosphorylative step of the Na-K-ATPase system, employing p-nitrophenylphosphate as a substrate and strontium as a capture ion for hydrolyzed phosphate. This phosphatase activity required external K (57) and internal Mg (56), but not Na (57), and could be inhibited by ouabain (31). Many similarities between this p-nitrophenylphosphatase and Na-K-ATPase were well documented (4, 21, 29, 51, 61), and it is well established that K-NPPase is a part of Na-K-ATPase complex.…”

“…Enough biochemical evidence has accumulated to make it almost certain that K-dependent p-nitrophenylphosphatase (K-NPPase) activity inhibited by ouabain, a specific inhibitor to Na-K-ATPase, reflects this second step (2,4,23,31,56,57). As a method to localize the K-NPPase activity, Ernst proposed a two step (Sr-Pb) cytochemical method (14)(15)(16).…”

Cytochemical localization of ouabain-sensitive, K-dependent p-nitrophenylphosphatase in the rat hepatocyte.

“…The principle of this method is based on the fact that the hydrolysis of ATP by Na-K-ATPase occurs in at least two basic steps : (1) a (Na +Mg)-dependent phosphorylation of enzyme protein by ATP, and (2) a (K+Mg)-dependent, ouabain-sensitive dephosphorylation of the phosphorylated intermediate (44,47,52) . The latter can utilize an artificial substrate such as p-nitrophenyl phosphate (32) . Biochemically many similarities were well documented between this K-NPPase activity and Na-K-ATPase activity in the plasma membranes of the erythrocyte, kidney, brain and liver (1,3,26,39) .…”

Cytochemical Localization of Ouabain-sensitive, K+-dependentp-nitrophenylphosphatase Activity in the Facial Nerve of Reserpinized Guinea Pigs

“…Using a ceriumbased method (Kobayashi et al 1987), Kanoh et al (1993a) and Kanoh (1994) investigated the localization of K-NPPase activity in the stria vascularis of reserpinized guinea pigs and found that K-NPPase activity was decreased from Day 3 to Day 20 after reserpinization. K-NPPase is the second component of the Na,K-ATPase complex, which represents the dephosphorylation step in the sodium pump cycle (Judah et al 1962). In the present study, to clarify the cytochemical effects of reserpine, the localization of K-NPPase activity in the temporal portion of the facial nerve of guinea pigs was examined using a ceriumbased method.…”