Specific protein-protein interactions between the essential mammalian spliceosome-associated proteins SAP 61 and SAP 114.
Spliceosome-associated proteins (SAPs) 61, 62, and 114 can be UV-crosslinked to pre-mRNA in purified spliceosomal complexes and are associated with U2 small nuclear ribonucleoproteins (snRNP). These proteins also compose the essential heterotrimeric splicing factor SF3a, and products of yeast pre-mRNA processing genes PRP9, PRP11, and PRP21 are their likely yeast counterparts. We report the isolation of a cDNA encoding SAP 61 and find that it is 30% identical in amino acid sequence to PRP9. A C-terminal Cys2His2 zinc-finger-like motif, which could be involved in the pre-mRNA binding, is the most highly conserved region of the protein. We also demonstrate specific protein-protein interactions between SAPs 61 and 114 and show that the N terminus of SAP 61 is required for this interaction. Significantly, the corresponding proteins are also known to interact in yeast: PRP9 interacts with PRP21, and the N-terminal portion of PRP9 is required. Previous work showed that direct interactions also occur between SAPs 62 and 114 and between the corresponding PRPs 11 and 21. These observations indicate that the specific protein-protein interactions that occur between the three prespliceosomal factors have been conserved between yeast and mammals.
Department of Cardiology, Children's Hospital, Boston, MA 02115.
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Chiara
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Champion-Arnaud
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Buvoli
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Nadal-Ginard
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Reed
D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D017124:Conserved Sequence; D005656:Fungal Proteins / Q000096:biosynthesis / Q000737:chemistry; D005800:Genes, Fungal; D006367:HeLa Cells; D006801:Humans; D008322:Mammals; D008969:Molecular Sequence Data; D011485:Protein Binding; D012322:RNA Precursors / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional / Q000235:genetics; D000072260:RNA Splicing Factors; D012333:RNA, Messenger / Q000096:biosynthesis; D016601:RNA-Binding Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D017413:Ribonucleoprotein, U2 Small Nuclear; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D017381:Spliceosomes / Q000378:metabolism*
D005656:Fungal Proteins; C065574:PRP9 protein, S cerevisiae; D012322:RNA Precursors; D000072260:RNA Splicing Factors; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D017413:Ribonucleoprotein, U2 Small Nuclear; C088050:SF3A1 protein, human; D029701:Saccharomyces cerevisiae Proteins; C088049:splicing factor 3a