Interactions between small nuclear ribonucleoprotein particles in formation of spliceosomes

Cell. 1987 Jun 19;49(6):763-74. doi: 10.1016/0092-8674(87)90614-3.


Electrophoretic separation of ribonucleoprotein particles in a nondenaturing gel was used to analyze the splicing of mRNA precursors. Early in the reaction, a complex formed consisting of the U2 small nuclear ribonucleoprotein particle (snRNP) bound to sequences upstream of the 3' splice site. This complex is modeled as a precursor of a larger complex, the spliceosome, which contains U2, U4/6, and U5 snRNPs. Conversion of the U2 snRNP-precursor RNA complex to the spliceosome probably involves binding of a single multi-snRNP particle containing U4/6 and U5 snRNPs. The excised intron was released in a complex containing U5, U6, and probably U2 snRNPs. Surprisingly, U4 snRNP was not part of the intron-containing complex, suggesting that U4/6 snRNP disassembles and assembles during splicing. Subsequently, the reassembled U4/6 snRNP would associate with U5 snRNP and participate in de novo spliceosome formation. U1 snRNP was not detected in any of the splicing complexes.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • HeLa Cells
  • Humans
  • Macromolecular Substances
  • Nucleic Acid Precursors / metabolism*
  • RNA Splicing*
  • RNA, Messenger / metabolism*
  • RNA, Small Nuclear / physiology*
  • Ribonucleoproteins / physiology*
  • Ribonucleoproteins, Small Nuclear


  • Macromolecular Substances
  • Nucleic Acid Precursors
  • RNA, Messenger
  • RNA, Small Nuclear
  • Ribonucleoproteins
  • Ribonucleoproteins, Small Nuclear