Term Name:	precatalytic spliceosome
Synonyms:	mammalian spliceosomal complex B, mammalian spliceosomal complex B1, yeast spliceosomal complex A2-1
Definition:	A spliceosomal complex that is formed by the recruitment of a preassembled U5-containing tri-snRNP to the prespliceosome. Although all 5 snRNPs are present, the precatalytic spliceosome is catalytically inactive. The precatalytic spliceosome includes many proteins in addition to those found in the associated snRNPs.
Ontology:	GO: Cellular Component [GO:0071011]    QuickGO    AmiGO