RNA-3-Terminal Phosphate Cyclase Like Protein (RCL1)

The RCL1 protein shares 97% amino sequence identity with the mouse homolog, which shares 38% identity with S. cerevisiae Rcl1. RCL1 and its homologs share similarity with RNA terminal phosphate cyclases, but they lack the conserved histidine residue that acts as an adenylate acceptor. Immunofluorescence studies localized both yeast and mouse Rcl1 and to the nucleolus.Rcl1 is required for viability in yeast and that depletion of Rcl1 caused slower growth characterized by a progressively increased doubling time. Rcl1-mutant strains showed decreased levels of 40S ribosomal subunits, resulting in decreases of 20S pre-rRNA and 18S rRNA levels. Northern blot analysis and primer extension confirmed defects in cleavage and processing of the yeast 35S pre-rRNA at the A0, A1, and A2 sites in Rcl1-mutant strains.