A protein factor, ASF, controls cell-specific alternative splicing of SV40 early pre-mRNA in vitro.
SV40 early pre-mRNA is alternatively spliced by utilization of two different 5' splice sites and a shared 3' splice site to produce large T and small t mRNAs. The ratio of small t to large T mRNAs produced in human embryonic kidney 293 cells is 10- to 20-fold greater than in other mammalian cells, suggesting the existence of a 293 cell-specific factor that modulates alternative splicing. Here we show that nuclear extracts from 293 cells give rise to significantly more small t splicing than do extracts from HeLa cells. Using an in vitro complementation assay, we have characterized and extensively purified a factor from 293 extracts that brings about striking increases in small t splicing with concomitant decreases in large T splicing. The factor is heat sensitive and micrococcal nuclease resistant, suggesting that it is a protein lacking an accessible RNA component. Purification of the alternative splicing factor indicates that the activity is contained in one of several possibly related polypeptides of 30-35 kd.
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Department of Biological Sciences, Columbia University, New York, New York 10027.
Manley
J L
JL
D001685:Biological Factors / Q000302:isolation & purification / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D004355:Drug Stability; D005816:Genetic Complementation Test; D006367:HeLa Cells / Q000378:metabolism; D006801:Humans; D007438:Introns; D008970:Molecular Weight; D010957:Plasmids; D012322:RNA Precursors / Q000235:genetics*; D012326:RNA Splicing; D012367:RNA, Viral / Q000235:genetics*; D013539:Simian virus 40 / Q000235:genetics*
D001685:Biological Factors; D012322:RNA Precursors; D012367:RNA, Viral