The mammalian analogue of the yeast PRP8 splicing protein is present in the U4/5/6 small nuclear ribonucleoprotein particle and the spliceosome.
HeLa cell nuclear extracts contain a protein reactive with antibodies against PRP8, a polypeptide essential for pre-mRNA splicing in yeast and a specific component of the yeast U5 small nuclear ribonucleoprotein (snRNP) [Lossky, M., Anderson, G. J., Jackson, S. P. & Beggs, J. (1987) Cell 51, 1019-1026]. The mammalian protein appears as a doublet at approximately 200 kDa, smaller than the 260-kDa yeast protein, and possesses an Sm epitope as determined by immunoblotting. Its association with a snRNP of the Sm class other than U1 or U2 is indicated by its immunoprecipitation by anti-Sm and anti-trimethylguanosine antibodies but not by anti-(U1) or anti-(U2) RNP sera. Gradient fractionation of splicing extracts demonstrates that the 200-kDa protein is a component of the U4/5/6 snRNP complex and of U5 snRNPs. It is also present in affinity-purified spliceosomes.
Pinto
A L
AL
Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510.
Steitz
J A
JA
D000911:Antibodies, Monoclonal; D002467:Cell Nucleus / Q000032:analysis; D002499:Centrifugation, Density Gradient; D004722:Endoribonucleases; D000939:Epitopes / Q000032:analysis; D005656:Fungal Proteins / Q000032:analysis*; D006367:HeLa Cells / Q000032:analysis; D006801:Humans; D008970:Molecular Weight; D012326:RNA Splicing; D016914:Ribonuclease H; D012261:Ribonucleoproteins / Q000032:analysis*; D017411:Ribonucleoproteins, Small Nuclear; D012441:Saccharomyces cerevisiae / Q000032:analysis*
D000911:Antibodies, Monoclonal; D000939:Epitopes; D005656:Fungal Proteins; D012261:Ribonucleoproteins; D017411:Ribonucleoproteins, Small Nuclear; D004722:Endoribonucleases; D016914:Ribonuclease H