A novel SR-related protein is required for the second step of Pre-mRNA splicing.
The SR family proteins and SR-related polypeptides are important regulators of pre-mRNA splicing. A novel SR-related protein of an apparent molecular mass of 53 kDa was isolated in a gene trap screen that identifies proteins which localize to the nuclear speckles. This novel protein possesses an arginine- and serine-rich domain and was termed SRrp53 (for SR-related protein of 53 kDa). In support for a role of this novel RS-containing protein in pre-mRNA splicing, we identified the mouse ortholog of the Saccharomyces cerevisiae U1 snRNP-specific protein Luc7p and the U2AF65-related factor HCC1 as interacting proteins. In addition, SRrp53 is able to interact with some members of the SR family of proteins and with U2AF35 in a yeast two-hybrid system and in cell extracts. We show that in HeLa nuclear extracts immunodepleted of SRrp53, the second step of pre-mRNA splicing is blocked, and recombinant SRrp53 is able to restore splicing activity. SRrp53 also regulates alternative splicing in a concentration-dependent manner. Taken together, these results suggest that SRrp53 is a novel SR-related protein that has a role both in constitutive and in alternative splicing.
Cazalla
Demian
D
MRC Human Genetics Unit, Western General Hospital, Crewe Rd., Edinburgh EH4 2XU, Scotland, United Kingdom.
Newton
Kathryn
K
Cáceres
Javier F
JF
D017398:Alternative Splicing / Q000235:genetics / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D002467:Cell Nucleus / Q000737:chemistry; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D012322:RNA Precursors / Q000378:metabolism*; D022821:RNA Splice Sites / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques
C084105:HCC1 autoantigen; C404083:LUC7L3 protein, human; D009687:Nuclear Proteins; D012322:RNA Precursors; D022821:RNA Splice Sites; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C500608:SRrp53 protein, mouse