Alternative titles; symbols
HGNC Approved Gene Symbol: NOL6
Cytogenetic location: 9p13.3 Genomic coordinates (GRCh38) : 9:33,461,353-33,473,924 (from NCBI)
By screening a mouse embryonic stem cell cDNA library with a partial Nol6 clone, followed by 5-prime RACE, database analysis, and RT-PCR of human hepatic cell line RNA, Utama et al. (2002) cloned full-length human and mouse NOL6, which they called NRAP. They identified NOL6-alpha, -beta, and -gamma isoforms that contain 1,146, 1,007, and 699 amino acids, respectively. NOL6-alpha shares 88% amino acid identity with mouse Nol6-alpha. Both human and mouse coding regions are GC-rich and share weak homology to a PAP/25A core domain, which is found in poly(A) polymerases (605553). NOL6 contains potential nuclear localization signals and has several potential phosphorylation sites. Immunohistochemical and immunofluorescence studies localized Nol6 expression within the nucleolus in a variety of rodent cell lines, although expression was not specifically localized to rRNA transcription sites. Nol6 localized to the condensed chromosomes during mitosis in a pattern similar to that of B23/nucleophosmin (NPM1; 164040). In situ hybridization studies in mouse embryos showed ubiquitous Nol6 expression during development. Immunoblot studies of mouse tissues detected strong expression in spleen, testis, colon, kidney, stomach, and brain, with moderate expression in lung, liver, and small intestine, and low expression in heart and skeletal muscle.
By database analysis, Bernstein et al. (2004) identified NOL6 as the human ortholog of yeast Utp22. Utp22 is a component of a yeast ribonucleoprotein required for biogenesis of the 18S rRNA.
Utama et al. (2002) showed that both actinomycin D and RNase treatment disrupted Nol6 nucleolar localization while cyclohexamide had no effect. They suggested that Nol6 interacts either directly or indirectly with the pre-rRNA transcript.
Utama et al. (2002) determined that the NOL6 gene contains 26 exons spanning 11.4 kb. Alternative splicing excludes exons 24 and 25 in NOL6-beta and skips exons 16 to 25 in the NOL6-gamma isoform.
By genomic sequence analysis, Utama et al. (2002) mapped the NOL6 gene to chromosome 9p13.
Bernstein, K. A., Gallagher, J. E. G., Mitchell, B. M., Granneman, S., Baserga, S. J. The small-subunit processome is a ribosome assembly intermediate. Eukaryotic Cell 3: 1619-1626, 2004. [PubMed: 15590835] [Full Text: https://doi.org/10.1128/EC.3.6.1619-1626.2004]
Utama, B., Kennedy, D., Ru, K., Mattick, J. S. Isolation and characterization of a new nucleolar protein, Nrap, that is conserved from yeast to humans. Genes Cells 7: 115-132, 2002. [PubMed: 11895476] [Full Text: https://doi.org/10.1046/j.1356-9597.2001.00507.x]