Term Name:	generation of catalytic spliceosome for first transesterification step
Synonyms:	catalytic spliceosome assembly for first transesterification step, formation of catalytic spliceosome for first transesterification step, spliceosomal A2-2 complex biosynthesis, spliceosomal A2-2 complex formation, spliceosomal C1 complex biosynthesis, spliceosomal C1 complex formation, U12-type catalytic spliceosome formation for first transesterification step, U2-type catalytic spliceosome formation for first transesterification step
Definition:	Formation of a catalytic spliceosome complex ready to perform the first splicing reaction. This occurs by an ATP-dependent conformational change of the pre-catalytic spliceosome.
Ontology:	GO: Biological Process [GO:0000349]    QuickGO    AmiGO