Ribonuclease P/MRP 38kDa Subunit (RPP38)

RPP38 is a major target for antisera from systemic sclerosis patients and that the antigen is likely to be localized in both the nucleoplasm and nucleolus. Immunoprecipitation analysis showed that polyclonal antibodies raised against RPP20, RPP30, RPP38, or RPP40 interact with RNase P from HeLa cells.The deduced 283-amino acid protein has a leucine zipper RNA-binding motif and a predicted molecular mass of nearly 32 kD, less than the 38 kD observed in SDS-PAGE analysis.Targeted cleavage of the H1RNA (RPPH1) moiety of RNase P altered enzyme specificity and diminished Pol III transcription. Similarly, inactivation of RNase P protein subunits, such as RPP38, by small interfering RNA inhibited Pol III function and Pol III-directed promoter activity in the cell.