Contribution of breakdown in the regulation of mouse liver glutathione S-transferase subunits during protein depletion and re-feeding

The in vivo radioactivity decay of glutathione S-transferase (GST) was observed in livers of normal-fed (N), protein-depleted (D), and re-fed mice (R), labelled with [S-35]methionine. Half-lives in days at N, D and R, respectively, were: total GST, 1.7, 1.4, 4.3; Yb1-subunit, 2.0, 1.8, 3.3; Yc-subunit, 2.4, 1.0, 4.2; Yf-subunit, 1.1, 2.1, 5.0. These findings, together with the fact that the proportions of GST-subunits depend on dietary-protein, show that breakdown contributes differentially to control the content of each GST subunit. Data also indicate that GSTs are long-life proteins. (C) 1998 Elsevier Science B.V. All rights reserved.