has part Prp19 complex spliceosomal complex U5 snRNP catalytic step 1 spliceosome cellular_component yeast spliceosomal complex A1 mammalian spliceosomal complex B2 activated spliceosome mammalian spliceosomal complex B* GO:0071012 mah A spliceosomal complex that is formed by the displacement of the two snRNPs from the precatalytic spliceosome; three snRNPs including U5 remain associated with the mRNA. This complex, sometimes called the activated spliceosome, is the catalytically active form of the spliceosome, and includes many proteins in addition to those found in the associated snRNPs. 2009-07-30T12:00:35Z catalytic complex