Cdc5p remains in a large complex in pre-mRNA splicing mutants. (A) Lysates from prp1-1 cdc5-TAP, prp2-1 cdc5-TAP, prp4-1 cdc5-TAP, and prp12-1 cdc5-TAP strains after 3 h at 36°C, probed with anti-Cdc5p antibodies. Migration of FAS (40S), thyroglobulin (19S), and catalase (11.3S) collected from parallel gradients is indicated. (B) RT-PCR analysis of cdc2+ RNA isolated from wild-type (lane 2), prp1-1 cdc5-TAP (lane 3), prp2-1 cdc5-TAP (lane 4), prp4-1 cdc5-TAP (lane 5), and prp12-1 cdc5-TAP (lane 6) strains after 2 h at 36°C. Lane 1 represents a mock RT-PCR that lacks RNA but includes all other components of the reaction. PC, precursor; M, mature.