Isolation and purification of U7 snRNP particles.

1. A procedure has been developed for the isolation of U7 small nuclear ribo-protein particles involved in the processing of histone pre-mRNAs. They were fractionated from the rest of the snRNPs through a series of gel filtration and affinity chromatography steps. 2. The isolated assembly of U7 snRNP particles appeared to be intact and pure as judged by the gel electrophoresis of their RNA. No detectable RNA species were monitored other than U7 RNA.