SSB-1 of the yeast Saccharomyces cerevisiae is a nucleolar-specific, silver-binding protein that is associated with the snR10 and snR11 small nuclear RNAs.
SSB-1, the yeast single-strand RNA-binding protein, is demonstrated to be a yeast nucleolar-specific, silver-binding protein. In double-label immunofluorescence microscopy experiments antibodies to two other nucleolar proteins, RNA Pol I 190-kD and fibrillarin, were used to reveal the site of rRNA transcription; i.e., the fibrillar region of the nucleolus. SSB-1 colocalized with fibrillarin in a double-label immunofluorescence mapping experiment to the yeast nucleolus. SSB-1 is located, though, over a wider region of the nucleolus than the transcription site marker. Immunoprecipitations of yeast cell extracts with the SSB-1 antibody reveal that in 150 mM NaCl SSB-1 is bound to two small nuclear RNAs (snRNAs). These yeast snRNAs are snR10 and snR11, with snR10 being predominant. Since snR10 has been implicated in pre-rRNA processing, the association of SSB-1 and snR10 into a nucleolar snRNP particle indicates SSB-1 involvement in rRNA processing as well. Also, another yeast protein, SSB-36-kD, isolated by single-strand DNA chromatography, is shown to bind silver under the conditions used for nucleolar-specific staining. It is, most likely, another yeast nucleolar protein.
Clark
M W
MW
Division of Biology, California Institute of Technology, Pasadena 91125.
Yip
M L
ML
Campbell
J
J
Abelson
J
J
D000906:Antibodies; D001323:Autoantibodies; D001324:Autoantigens / Q000032:analysis*; D002352:Carrier Proteins / Q000032:analysis*; D002868:Chromosomal Proteins, Non-Histone / Q000276:immunology; D004268:DNA-Binding Proteins / Q000032:analysis; D005455:Fluorescent Antibody Technique; D005656:Fungal Proteins / Q000032:analysis*; D006801:Humans; D008856:Microscopy, Fluorescence; D008970:Molecular Weight; D009697:Nucleolus Organizer Region / Q000737:chemistry*; D011233:Precipitin Tests; D012323:RNA Processing, Post-Transcriptional; D012331:RNA, Fungal / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000378:metabolism; D012342:RNA, Small Nuclear / Q000378:metabolism*; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D012270:Ribosomes / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000032:analysis* / Q000235:genetics; D012834:Silver / Q000378:metabolism; D012965:Sodium Chloride; D000097585:SS-B Antigen
D000906:Antibodies; D001323:Autoantibodies; D001324:Autoantigens; D002352:Carrier Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D012331:RNA, Fungal; D012335:RNA, Ribosomal; D012342:RNA, Small Nuclear; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D012834:Silver; D012965:Sodium Chloride; D000097585:SS-B Antigen; C047458:fibrillarin