Up-regulation of sodium pump activity in Xenopus laevis oocytes by expression of heterologous beta 1 subunits of the sodium pump.

摘要: Recent evidence suggests that the beta subunit of Na+ pump is essential for alpha to express catalytic activity and assembly holoenzyme in plasma membrane. We report here injection into Xenopus laevis oocytes cRNAs specific 1 isoforms four species (Torpedo californica, chicken, mouse rat) causes a time-dependent increase number ouabain-binding sites, both membrane internal membranes. Expression rat could be substantiated by immunoprecipitation using polyclonal antiserum against subunit. Scatchard analysis permeabilized cells disclosed affinity ouabain unchanged after expression each subunits. A proportional ouabain-sensitive 86Rb+ uptake indicates additionally expressed sites on cell surface represent functional pumps. The findings support concept Geering. Theulaz, Verrey, Hauptle & Rossier [(1989) Am. J. Physiol. 257, C851-C858] subunits associate with an excess endogenous form hybrid enzyme. In addition, all investigated present study were also capable combining co-expressed Torpedo produce Injection cRNA encoding alone had no effect capacity intracellular membranes oocyte.