HGNC Approved Gene Symbol: SURF6
Cytogenetic location: 9q34.2 Genomic coordinates (GRCh38): 9:133,328,776-133,336,188 (from NCBI)
Magoulas and Fried (1996) isolated mouse Surf6. The deduced mouse Surf6 protein contains 355 amino acids and is highly basic. Surf6 has features common to housekeeping genes, including ubiquitous expression of its transcript. Immunofluorescence and immunoblot analyses localized the Surf6 protein to the nucleolus. Immunocytochemical microscopy localized Surf6 predominantly in the nucleolar granular component, a structure involved in ribosome maturation.
By screening a human fetal brain cDNA library with mouse Surf6, followed by 5-prime RACE of lymphocyte RNA, Magoulas and Fried (2000) cloned human SURF6. The deduced 361-amino acid protein has a calculated molecular mass of 41.2 kD, is highly basic, and has putative nuclear localization motifs. SURF6 shares 72% identity with the mouse protein. Northern blot analysis showed ubiquitous expression of a major 2.0-kb transcript, and a minor 4.2-kb transcript was also detected in some tissues.
Magoulas et al. (1998) found that recombinant mouse Surf6 bound RNA with high affinity and DNA with lower affinity. Immunofluorescence analysis of synchronized mouse fibroblasts showed that Surf6 maintained a nucleolar localization during the cell cycle, but it did not completely colocalize with the major nucleolar proteins B23 (NPM1; 164040) and fibrillarin (FBL; 134795) during interphase and mitosis. Magoulas et al. (1998) proposed that SURF6 may support nucleolar matrix structure and function via its association with nucleic acids, and that it may be involved in processing rRNA.
Romanova et al. (2006) found that Surf6 mRNA was expressed in mouse oocytes and was maternally inherited in the zygote. Surf6 first became clearly visible in the nuclei of mid 2-cell embryos, where it accumulated around nucleolar precursor bodies that were likely Cajal (coiled) bodies. In 4- and 8-cell embryos, Surf6 remained at the nucleolar precursor body periphery, but its localization was more extended than in 2-cell embryos. In morulae and blastocysts, Surf6 localization was essentially similar to that in nucleoli of mouse somatic cells. Knockdown of Surf6 expression by RNA interference led to developmental arrest at the 8-cell/morula stage, as well as a decrease in the level of 18S rRNA. Romanova et al. (2006) concluded that SURF6 accumulates in oocytes and embryo nuclei when they are transcriptionally competent, and that its localization is similar but not identical to that of B23 and fibrillarin.
Magoulas and Fried (2000) determined that the SURF6 gene contains 5 exons and spans about 4.3 kb. It has at least 2 transcription start sites. The upstream region contains a CpG island but no TATA motif, and the intronic regions contain 4 repetitive Alu elements.
The SURF6 gene is located within the surfeit gene cluster in chromosome 9q34.1 (Yon et al., 1993). By sequence analysis, Magoulas and Fried (2000) determined that the 5-prime end of the SURF6 gene and the 3-prime end of the SURF5 gene (MED22; 185641) are separated by 3.2 kb, and that the intergenic region contains a processed pseudogene of RPL21 (603636).
Magoulas, C., Fried, M. Isolation and genomic analysis of the human Surf-6 gene: a member of the Surfeit locus. Gene 243: 115-123, 2000. [PubMed: 10675619] [Full Text: https://doi.org/10.1016/s0378-1119(99)00551-x]
Magoulas, C., Fried, M. The Surf-6 gene of the mouse surfeit locus encodes a novel nucleolar protein. DNA Cell Biol. 15: 305-316, 1996. [PubMed: 8639267] [Full Text: https://doi.org/10.1089/dna.1996.15.305]
Magoulas, C., Zatsepina, O. V., Jordan, P. W. H., Jordan, E. G., Fried, M. The SURF-6 protein is a component of the nucleolar matrix and has a high binding capacity for nucleic acids in vitro. Europ. J. Cell Biol. 75: 174-183, 1998. [PubMed: 9548374] [Full Text: https://doi.org/10.1016/S0171-9335(98)80059-9]
Romanova, L. G., Anger, M., Zatsepina, O. V., Schultz, R. M. Implication of nucleolar protein SURF6 in ribosome biogenesis and preimplantation mouse development. Biol. Reprod. 75: 690-696, 2006. [PubMed: 16855206] [Full Text: https://doi.org/10.1095/biolreprod.106.054072]
Yon, J., Jones, T., Garson, K., Sheer, D., Fried, M. The organization and conservation of the human Surfeit gene cluster and its localization telomeric to the c-ABL and CAN proto-oncogenes at chromosome band 9q34.1. Hum. Molec. Genet. 2: 237-240, 1993. [PubMed: 8499913] [Full Text: https://doi.org/10.1093/hmg/2.3.237]