Block Of Proliferation 1 (BOP1)

Bop1 was required for proper processing of pre-rRNA at distinct sites within the internal transcribed spacers ITS1 and ITS2 and at the 3-prime external spacer.The deduced 682-amino acid protein contains beta-transducin repeats. BOP1 expression in all tissues examined, with highest levels in skeletal muscle and colon.The deduced 732-amino acid protein has a calculated molecular mass of 83 kD. It has 2 PEST sequences in its N-terminal half and 4 WD40 repeats in its C-terminal half. Northern blot analysis detected Bop1 expression in all mouse tissues examined. Immunofluorescence staining localized endogenous and epitope-tagged Bop1 predominantly to nucleoli, although weak, diffuse nucleoplasmic staining was also present. Western blot analysis detected endogenous Bop1 at an apparent molecular mass of 100 kD.