NOA36 Protein Contains a Highly Conserved Nucleolar Localization Signal Capable of Directing Functional Proteins to the Nucleolus, in Mammalian Cells

de Melo, Ivan S.; Jimenez-Nuñez, Maria D.; Iglesias, Concepción; Campos-Caro, Antonio; Moreno-Sanchez, David; Ruiz, Felix A.; Bolívar, Jorge

We also have demonstrated that the NoLS of NOA36 can be used to target the expression of yeast exopolyphophatase in the nucleolus of the HeLa cell. Polyphosphate is a ubiquitous polymer, formed by phosphate (Pi) residues, that directly regulates several processes in the cell and is used as a phosphate donor in gene regulation [52] . In mammalian cells, the enzymes involved in polyphosphate metabolism are still unknown; therefore, new tools to specifically modify subcellular levels of polyphosphate should be very useful. We recently have described the nucleolar localization of polyphosphate in eukaryotic cells, which is associated with nucleolar transcription by modulating the RNA Pol I activity [39] . As myeloma cancer cells have an exceptionally high level of polyphosphate in the nucleolus [39] , the NOA36 NoLS-scPPX construction could be of special interest for prospective studies to understand the function of nucleolar polyphosphate on the biology of myeloma cells.