A complex is formed upon incubation of a precursor mRNA (pre-mRNA) with HeLa cell nuclear extract in the absence of added ATP (-ATP complex). Pre-mRNAs with mutations in the 5′ splice site, the 3′ splice site, or the polypyrimidine tract did not form this complex. Once formed, the -ATP complex was stable to competition by excess pre-mRNA. The complex was shown to contain the U2 small nuclear ribonucleoprotein particle (snRNP) and was distinct from the previously described U2 snRNP/pre-mRNA complex, the prespliceosome. These complexes have different electrophoretic mobilities, ATP requirements, and sensitivities to mutations of the 5' splice site. Although U1 snRNP was not found in the -ATP complex, a requirement for the U1 snRNP was suggested by immunodepletion experiments. The possible implications for the study of spliceosome formation are discussed.
|Original language||English (US)|
|Number of pages||5|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|State||Published - 1992|
- Precursor mRNA splicing
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