Nuclear localization properties of a conserved protuberance in the Sm core complex.
The nuclear import signal of snRNPs is composed of two essential components, the m(3)G cap structure of the snRNA and the Sm core NLS carried by the Sm protein core complex. We have previously proposed that, in yeast, this last determinant is represented by a basic-rich protuberance formed by the C-terminal extensions of Sm proteins. In mammals, as well as in other organisms, this component has not yet been precisely defined. Using GFP-Sm fusion constructs and immunolocalization as well as biochemical experiments, we show here that the C-terminal domains of human SmD1 and SmD3 proteins possess nuclear localization properties. Deletions of these domains increase cytoplasmic fluorescence and cytoplasmic localization of GFP-Sm mutant fusion alleles. Our results are consistent with a model in which the Sm core NLS is evolutionarily conserved and composed of a basic-rich protuberance formed by C-terminal domains of different Sm subtypes.
Institut de Génétique Moléculaire, IFR122, CNRS UMR 5535, Montpellier, France.
Cyrille
C
Girard
John
J
Mouaikel
Henry
H
Neel
Edouard
E
Bertrand
Rémy
R
Bordonné
D021581:Active Transport, Cell Nucleus / Q000235:genetics; D000818:Animals; D001324:Autoantigens; D002467:Cell Nucleus / Q000235:genetics* / Q000378:metabolism*; D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism; D019143:Evolution, Molecular; D006801:Humans; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D010802:Phylogeny; D017434:Protein Structure, Tertiary / Q000235:genetics; D012342:RNA, Small Nuclear / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017411:Ribonucleoproteins, Small Nuclear / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D055517:snRNP Core Proteins
D001324:Autoantigens; D046911:Macromolecular Substances; D012342:RNA, Small Nuclear; D011993:Recombinant Fusion Proteins; D017411:Ribonucleoproteins, Small Nuclear; C091107:SMD3 protein, S cerevisiae; C526409:SNRPD1 protein, human; C526412:SNRPD3 protein, human; D029701:Saccharomyces cerevisiae Proteins; D055517:snRNP Core Proteins