Fig. 3. Anti-huACF immunoprecipitation of rat p66 cross-linked to apoB RNA. (A) In vitro editing reactions containing rat liver nuclear extract and either radiolabeled apoB or control RNA (WT-1) were immunoprecipitated with anti-huACF at varying times during a 60 minute reaction and without RNase digest, subjected to immunoprecipitation with anti-huACF antibody bound to Protein A beads. The amount of RNA recovered in the immunoprecipitate was determined by scintillation counting washed beads. (B) In vitro editing reactions containing recombinant huACF or rat liver nuclear extract and radiolabeled apoB RNA, together with 1,000-fold molar excess of either WT-1 or apoB RNA (as indicated above each lane) were UV cross-linked after 60 minutes of reaction, RNase digested and then subjected to immunoprecipitation with anti-huACF antibodies. Immunoprecipitates were resolved on 10% SDS PAGE and autoradiographed.