catalytic step 1 spliceosome
activated spliceosome
exact
mammalian spliceosomal complex B*
narrow
mammalian spliceosomal complex B2
narrow
yeast spliceosomal complex A1
narrow
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.
GO:0005681
spliceosomal complex
is_a
GO:1902494
catalytic complex
is_a
SPAC29A4.08c SPCC550.02c SPBC19C2.01 SPAC9.13c SPAC3A12.11c