Fibrillarin Recombinant Rabbit mAb (S-1718-171)

Fibrillarin is an evolutionarily conserved, 34-kDa nucleolar methyltransferase that is essential for 2'-O-methylation of pre-ribosomal RNA and pre-assembly of small nucleolar ribonucleoprotein (snoRNP) complexes on nascent ribosomal RNA, thereby driving early steps of ribosome biogenesis; it contains an N-terminal glycine- and arginine-rich (GAR) domain that mediates nucleolar localization and interaction with box C/D snoRNAs, followed by a central RNA-binding domain and a C-terminal S-adenosyl-L-methionine-dependent methyltransferase motif, localizes predominantly to the dense fibrillar component of the nucleolus in an Nop56/Nop58- and 15.5 kDa protein-dependent manner, and is recruited to sites of rDNA transcription by UBF and SL1; mutations or depletion of fibrillarin impair rRNA processing, leading to defects in 18S and 28S rRNA maturation, nucleolar stress, cell-cycle arrest, and embryonic lethality in model organisms, while in humans its overexpression is linked to several cancers and its absence causes the neurodevelopmental disorder Néstor-Guillermo progeria syndrome, underscoring its dual role as a guardian of ribosome production and a sensor of nucleolar integrity.