Fibrillarin (FBL, 34kD Nucleolar Scleroderma Antigen, rRNA 2'-O-methyltransferase Fibrillarin, FLRN, FIB1, Nop1p, RNU3IP1)

Nop1p was originally identified as a nucleolar protein of bakers yeast, Saccharomyces cerevisiae (accession P15646). The Nop1p protein is 327 amino acids in size (34.5kD), is essential for yeast viability, and is localized in the nucleoli (1). The systematic name for S. cerevisiae Nop1 is YDL014W, and it is now known to be part of the small subunit processome complex, involved in the processing of pre-18S ribosomal RNA. Nop1p is the yeast homolog of a protein apparently found in all eukaryotes and archea generally called fibrillarin. Fibrillarin/Nop1p is extraordinarily conserved, so that the yeast and human proteins are 67% identical, and the human protein can functionally replace the yeast protein. This means that suitably crossreactive antibodies to Nop1p/fibrillarin, like 031359, can be used to reveal nucleoli and study fibrillarin/Nop1p in all eukaryotes and archea tested to date. Human fibrillarin has been characterized (accession P22087) and the human fibrillarin gene is located on chromosome 19 (19q13.1). Fibrillarin/Nop1p proteins have been cloned and sequenced from several other species (e.g. Mouse, accession P35550, Xenopus accession P22232, C. elegans accession Q22053, and S. pombe accession P35551. The N-terminal ~80 amino acids contain multiple copies based on the peptide RGG, or arginine-glycine-glycine, sometimes referred to as GAR repeats, characteristic of the GAR family of molecules. The remaining ~240 amino acids consist of the so called fibrillarin domain. A fibrillarin homolog has also been identified in the genome of the archean Methanococcus (accession NC_000909). This protein lacks the RGG rich N-terminal extension but is clearly homologous to the other sequences throughout all of the fibrillarin domain. The 3D structure of this molecule has been determined and shown to consist of 2 extended b-sheets flanked by 4 a-helixes. Patients with the autoimmune disease scleroderma often have strong circulating autoantibodies to a ~34kD protein which was subsequently found to be fibrillarin. Recent studies show that knock out of the fibrillarin gene in mice results in embryonic lethality, although mice with only one functional fibrillarin/Nop1p gene were viable (3). This antibody is becoming widely used as a convenient marker for nucleoli in a wide variety of species (e.g. 4-6). The HGNC name for this protein is FBL.\n\nApplications:\nSuitable for use in Immunofluorescence and Western Blot. Other applications not tested.\n\nRecommended Dilution:\nImmunofluorescence: For immunofluorescence on yeast cells, use diluted 1:1000-1:5000. For IF of mammalian cells, try at 1:500.\nWestern Blot: For yeast protein samples, use diluted 1:2000 (cell lysates) to 1:10,000 (nuclear fractions), followed by chemiluminescent detection (ECL). For other (non-ECL) Western detection methods, try diluted 1:1000-1:5000. To detect mammalian fibrillarin on Western Blots by ECL, try at 1:500 dilution.\nOptimal dilutions to be determined by the researcher.\n\nStorage and Stability:\nMay be stored at 4 degrees C for short-term only. Aliquot to avoid repeated freezing and thawing. Store at -20 degrees C. Aliquots are stable for 12 months. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.

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SPECIFICATIONS

Catalog Number

031359

Size

500ul

Applications

IF, WB

Hosts

Mouse

Reactivities

Hum, Rat, Dro/Arth, Yeast/Fun

Form

Supplied as a liquid in 10mM sodium azide.

P Type

Mab

Purity

Sterile-filtered cell culture fluid from an Integra CL-350 biochamber

Isotype

IgG1

References

1. Ochs RL, Lischwe MA, Spohn WH, Busch H. Fibrillarin: a new protein of the nucleolus identified by autoimmune sera. Biol Cell 54:123-133 (1985).\n\n2. Aris JP and Blobel G. Identification and characterization of a yeast nucleolar protein that is similar to a rat liver nucleolar protein. J. Cell Biol. 107:17-31 (1988).\n\n3. Newton K, Petfalski E, Tollervey D, Caceres JF. Fibrillarin is essential for early development and required for accumulation of an intron-encoded small nucleolar RNA in the mouse. Mol Cell Biol. 23:8519-8527 (2003).\n\n4. Tyagi S and Alsmadi O. Imaging native beta-actin mRNA in motile fibroblasts. Biophys J. 87:4153-62 (2004).\n\n5. Paeschke1 K, Simonsson T, Postberg J, Rhodes D, Lipps H-J. Telomere end-binding proteins control the formation of G-quadruplex DNA structures in vivo Nature Structural & Molecular Biology 12, 847-854 (2005).\n\n6. Vermaak D, Henikoff S, Malik HS. Positive selection drives the evolution of rhino, a member of the heterochromatin protein 1 family in Drosophila. PLoS Genetics 1:96-108 (2005).

Additional Info

Recognizes fibrillarin in a wide variety of species including human, rat, Drosophila, S. pombe, C. elegans, and plants. It can therefore be used to identify nucleoli immunocytochemically.