Figure 6.

Estrogen-induced increase in PMR1 unit activity. Polysomes and mRNP complexes isolated from control and 24 h estrogen-treated frogs were normalized by scanning densitometry to equal amounts of immunoreactive PMR1. These were incubated with a uniformly ³²P-labeled 160 nt albumin transcript (18) or a full-length ³²P-labeled ferritin transcript for the indicated times and separated on a denaturing polyacrylamide–urea gel. The input transcript is denoted R in lane 2. The units of PMR1 enzymatic activity were determined by phosphorimager analysis of data obtained from the resulting albumin RNA decay curves. One unit of PMR1 activity equals the amount of enzyme that completely degrades 7 fmol albumin transcript substrate in 30 min at 22°C (17).