| Modification Notes |
NNP-1B (novel nuclear protein 1B), also known as RRP1-like protein B (Rrp1b) in mouse and rat, is a 758 amino acid protein belonging to the RRP1 family. Localized to the nucleolus, NNP-1B is expressed as two isoforms produced by alternative splicing. Ubiquitously expressed, the N-terminus of NNP-1B is 80% homologous to fellow RRP1 family member NNP-1, but has a divergent C-terminus. NNP-1 has been found to play an important role in the generation of 28S rRNA in the late processing steps of ribosome biogenesis. At the end of mitosis, nucleolar proteins assemble in a sequential order during the rebuilding of the nucleolus. NNP-1 assembles after Fibrillarin and C23, and simultaneously with B23 and POP1 in the prenucleolar body pathway. |