Figure 9.

Substitution of Tyr-10 by either Ala (Y10A) or Glu (Y10E) does not alter the stimulation of Na⁺,K⁺-ATPase by PMA in transfected OK cells. ⁸⁶Rb (K) uptake was measured in the presence of 5 × 10⁻⁶ M ouabain under initial rates of influx in OK cells expressing the WT rat α1-subunit and its tyrosine phosphorylation site mutants (Y10A and Y10E). Cells were preincubated for 30 min in the absence (C) or presence of 10⁻⁶ M PMA (P). Results are expressed as a percentage of control and are means ± SEM from six independent experiments (* p < 0.05 vs. control). In each cell line studied, the ouabain-insensitive ⁸⁶Rb (K) uptake was not altered by PMA.