InterPro domain: IPR007718

This presumed domain is found at the C terminus of the budding yeast Srp40 and mammalian NOLC1 (also known as Nopp140) proteins. They are nucleolar proteins that contain a central domain consisting of ten repeats of acidic serine clusters alternating with lysine-, alanine- and proline-rich basic stretches [ 1 ]. Srp40 may be involved in preribosome assembly or transport [ 2 ]. Human NOLC1 interacts with casein kinase 2 (CK2), RNA polymerase I, p80 coilin , NAP57, and both major classes (box H/ACA and box C/D) of snoRNPs [ 3 ]. It acts as a regulator of RNA polymerase I by connecting RNA polymerase I with enzymes responsible for ribosomal processing and modification [ 3 , 4 ].

1. Structural disorder and local order of hNopp140. Biochim. Biophys. Acta 1834, 342-50
2. The Srp40 protein plays a dose-sensitive role in preribosome assembly or transport and depends on its carboxy-terminal domain for proper localization to the yeast nucleoskeleton. DNA Cell Biol. 16, 1161-73
3. Human Nopp140, which interacts with RNA polymerase I: implications for rRNA gene transcription and nucleolar structural organization. Mol. Cell. Biol. 19, 8536-46
4. Cell-fate determination by ubiquitin-dependent regulation of translation. Nature 525, 523-7