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 []. Srp40 may be involved in preribosome assembly or transport []. 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 []. It acts as a regulator of RNA polymerase I by connecting RNA polymerase I with enzymes responsible for ribosomal processing and modification [, ].
