Fig. 3. Attachment of GSTs to the sperm plasma membrane evaluated after treatment of the plasma membranes with different reagents. The relative GST activity in 100,000 g supernatants of plasma membranes was measured (using 1 mM CDNB and GSH at a 2 minute time point) after treatment with (3) Pronase, 0.5 mg/ml, 10 minutes, (4) Trypsin, 0.5 mg/ml, 10 minutes, (5) Trypsin, 0.2 mg/ml, 10 minutes, (6) 20 mM HCl, 5 minutes, (7) 1 M NaCl, 15 minutes, (8) 0.1% NP 40, (9) PIPLC, 0.05 units/ml, 20 minutes. (1) The GST activity of the cytosol and (2) the GST activity of the plasma membrane. (Inset) Western blots (probed with anti-GST antibody at 1:1000 dilution). Lane a, total plasma membrane proteins; lane b, supernatant of treatment 7; lane c, GSH affinity-purified GSTs from the supernatant of treatment 7; m, molecular weight marker.

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