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The RNA processing enzyme RNase MRP is identical to the Th RNP and related to RNase P
H A Gold1, J N Topper, D A Clayton
1Department of Medicine, Yale University School of Medicine, New Haven, CT 06511.
Abstract:
Sera from patients with autoimmune diseases often contain antibodies that bind ribonucleoproteins (RNPs). Sera from 30 such patients were found to immunoprecipitate ribonuclease P (RNase P), an RNP enzyme required to process the 5' termini of transfer RNA transcripts in nuclei and mitochondria of eukaryotic cells. All 30 sera also immunoprecipitated the nucleolar Th RNP, indicating that the two RNPs are structurally related. Nucleotide sequence analysis of the Th RNP revealed it was identical to the RNA component of the mitochondrial RNA processing enzyme known as RNase MRP. Antibodies that immunoprecipitated the Th RNP selectively depleted murine and human cell extracts of RNase MRP activity, indicating that the Th and RNase MRP RNPs are identical. Since RNase P and RNase MRP are not associated with each other during biochemical purification, we suggest that these two RNA processing enzymes share a common autoantigenic polypeptide.
Insights
Autoimmune disease patients
Area of Science:
- Molecular biology
- Immunology
- Biochemistry
Background:
- Autoimmune diseases can feature antibodies targeting ribonucleoproteins (RNPs).
- Ribonucleoproteins (RNPs) are crucial for RNA processing in eukaryotic cells.
Purpose of the Study:
- To investigate the structural relationship between ribonuclease P (RNase P) and the nucleolar Th RNP.
- To identify the autoantigenic components shared between RNase P and RNase MRP.
Main Methods:
- Immunoprecipitation assays using sera from autoimmune patients.
- Nucleotide sequence analysis of the Th RNP.
- Assessing RNase MRP activity in cell extracts after antibody depletion.
Main Results:
- Sera from 30 autoimmune patients immunoprecipitated both RNase P and the nucleolar Th RNP.
- The Th RNP was identified as the RNA component of RNase MRP.
- Antibodies targeting the Th RNP also depleted RNase MRP activity, confirming their identity.
Conclusions:
- RNase P and RNase MRP are identical to the Th RNP autoantigen.
- These two distinct RNA processing enzymes likely share a common autoantigenic polypeptide.