Nucleolar Protein 14 (NOL14)

NOP14 plays a role in the processing of the pre-18S rRNA and small ribosomal subunit assembly. The central domain (amino acids 170 to 469) of yeast Nop14 interacted with Emg1 and that mouse Emg1 and human NOP14 interacted. Emg1 localized to both nuclear and cytoplasmic fractions in the presence of Nop14 but to the cytoplasmic fraction only in Nop14-depleted cells. Pulse-chase labeling of ribosomal RNA transcript processing in Nop14-depleted yeast showed a processing defect characterized by absence of the 18S rRNA species and its 20S precursor and normal levels of 25S rRNA, similar to the phenotype observed in Emg1 conditional mutant yeast. Sucrose density gradient profiling of cellular ribosomes and polysome runoff strains found significantly reduced levels of 40S subunits compared to 60S.