Figure 6.

Relative first step product yields over a range of potassium concentrations with chloride, acetate or glutamate counterions. (A) AdMLΔAG was incubated under standard splicing conditions for 60 min, except that KAc or KGlu and MgAc₂ were substituted for KCl and MgCl₂ according to the partial substitution conditions. Potassium concentrations were 60, 70, 80, 90, 100, 110 and 120 mM; lanes 1, 9 and 17 contained 80 mM potassium but were incubated for 0 min [used as input (I) values to calculate RNA stability]. The doublet bands present in this gel are due to 3′ end heterogeneity of the T7 transcript (41,42). (B) Indicated splicing efficiencies represent first step product species (lariat intermediate and 5′ exon) and were calculated as described in Materials and Methods.