Fig. 6. Immunodepletion of the 65 or the 110 kDa protein does not disrupt the U4/U6⋅U5 tri-snRNPs. (A) Western blot of mock-depleted extracts (lanes 2 and 6), 65 kDa-depleted extracts (lanes 3 and 8) and 110 kDa-depleted extracts (lanes 4 and 7) probed with anti-65 kDa or anti-110 kDa antibodies as indicated above each lane. In lanes 1 and 5, total snRNP proteins were blotted as a control. The bands correspond ing to the 65 and 110 kDa proteins are indicated. The bands corres ponding to the uncharacterized protein recognized by the anti-65 kDa antibody are marked with asterisks. (B) Immunoprecipitation of snRNPs with anti-U5 116 kDa antibodies from the mock-depleted (lane 1), 65 kDa-depleted (lane 2) and 110 kDa-depleted (lane 3) extracts. RNAs were isolated and identified by northern blot analysis.