spliceosomal complex assembly U2-type prespliceosome assembly major prespliceosome formation The aggregation, arrangement and bonding together of a set of components to form an U2-type prespliceosome. major prespliceosome assembly biological_process yeast U2-type spliceosomal complex B assembly mammalian U2-type spliceosomal complex A assembly yeast U2-type spliceosomal complex B formation mah GT-AG prespliceosome assembly U2-type prespliceosome formation mammalian U2-type spliceosomal complex A formation GT-AG prespliceosome formation 2014-08-01T14:33:45Z GO:1903241