Functional properties of p54, a novel SR protein active in constitutive and alternative splicing.

The p54 protein was previously identified by its reactivity with an autoantiserum. We report here that p54 is a new member of the SR family of splicing factors, as judged from its structural, antigenic, and functional characteristics. Consistent with its identification as an SR protein, p54 can function as a ...
constitutive splicing factor in complementing splicing-deficient HeLa cell S100 extract. However, p54 also shows properties distinct from those of other SR family members, p54 can directly interact with the 65-kDa subunit of U2 auxiliary factor (U2AF65), a protein associated with the 3' splice site. In addition, p54 interacts with other SR proteins but does not interact with the U1 small nuclear ribonucleoprotein U1-70K or the 35-kDa subunit of U2 auxiliary factor (U2AF35). This protein-protein interaction profile is different from those of prototypical SR proteins SC35 and ASF/SF2, both of which interact with U1-70K and U2AF35 but not with U2AF65. p54 promotes the use of the distal 5' splice site in E1A pre-mRNA alternative splicing, while the same site is suppressed by ASF/SF2 and SC35. These findings and the differential tissue distribution of p54 suggest that this novel SR protein may participate in regulation of alternative splicing in a tissue- and substrate-dependent manner.
Mesh Terms:
Alternative Splicing, Amino Acid Sequence, Animals, Blotting, Northern, Cell Line, DNA, Complementary, Epitopes, Gene Expression, Genetic Complementation Test, Hela Cells, Humans, Molecular Sequence Data, Nuclear Proteins, Nucleopolyhedrovirus, Organ Specificity, RNA Precursors, Sequence Homology, Amino Acid, Spodoptera, Transfection
Mol. Cell. Biol.
Date: Oct. 01, 1996
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