has part U12-type spliceosomal complex U11 snRNP U12 snRNP U4atac/U6atac x U5 tri-snRNP complex precatalytic spliceosome U12-type precatalytic spliceosome cellular_component mah AT-AC precatalytic spliceosome mammalian U12-type spliceosomal complex B GO:0071016 minor precatalytic spliceosome mammalian U12-type spliceosomal complex B1 yeast U12-type spliceosomal complex A2-1 2009-07-30T12:00:35Z A spliceosomal complex that is formed by the recruitment of the preassembled U4atac/U6atac.U5 tri-snRNP to the U12-type 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 U11, U12 and U4atac/U6atac.U5 snRNPs.