Influence of Glutathione Status on Sarcolemmal Protein Function

2 Influence of Glutathione Status on Sarcolemmal Protein Function 

1 Na/K Pump Structure and Regulatory Role of Sulphydryl Groups 

The Na/K ATPase has been extensively purified and characterized, and consists of a catalytic a subunit of around 95 kDa and a glycoprotein 0 subunit of approximately 45 kDa (Skou, 1992). The functional transporter exists as a dimer with each monomer consisting of an a and /3 subunit. Hiatt aal. (1984) have su ested that the non-catalytic jS subunit may be involved in the cottect insertion of the a subunit into the lipid bilayer and, therefore, it is conceivable that a modification of the 0 subunit structure may be reflected by changes in the catalytic activity of the a subunit. Therefore, in studies involving the manipulation of tissue glutathione levels, alterations of intracellular redox state may have an effect on substrate binding at an extracellular site on this ion-translocating protein. 

The direct effect of both reduced and oxidized glutathione on the activity of an isolated bovine ventricular 

50 ig/ml, or allopurinol (AP) 1 mu were added to the perfusion fluid 5 min before the onset of ischaemia and throughout the reperfusion period. Data are presented as the mean of 6-13 experiments and the bars represent the standard errors of the means. Asterisks indicate P 0.05, cf. value observed with ischaemia/reperfusion alone. Redrawn with permission from Kim and Akera (1987). 

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