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Purification of messenger RNA coding for glycine methyltransferase from rat liver
Abstract:
Rat liver messenger RNA coding for glycine methyltransferase was associated preferentially with free polysomes. The mRNA was purified about 1000-fold over the total poly(A)-containing RNA by specific immunoadsorption of polysomes to protein A-Sepharose followed by oligo(dT)-cellulose column chromatography. Sodium dodecyl sulfate-gel electrophoresis of the in vitro translation products in a rabbit reticulocyte lysate system revealed only one major band which migrated to the position of the purified glycine methyltransferase subunit. The result shows that the mRNA isolated is nearly homogeneous and suggests that no precursor form of the enzyme existed. The mRNA sedimented at the position slightly smaller than 18 S rRNA in a sucrose density-gradient centrifugation and was shown to contain about 1,300 nucleotides by the Northern blot hybridization analysis with a cDNA probe.
Insights
Researchers isolated messenger RNA (mRNA) for glycine methyltransferase from rat liver. This highly purified mRNA suggests no precursor enzyme form exists, with the mRNA containing approximately 1,300 nucleotides.
Area of Science:
- Biochemistry
- Molecular Biology
- Enzymology
Background:
- Glycine methyltransferase (GMT) is a key enzyme in cellular metabolism.
- Understanding the synthesis and regulation of GMT is crucial for metabolic research.
Purpose of the Study:
- To isolate and characterize the messenger RNA (mRNA) encoding rat liver glycine methyltransferase.
- To determine the purity and size of the GMT mRNA and investigate potential precursor forms.
Main Methods:
- Purification of poly(A)-containing RNA from rat liver polysomes using immunoadsorption and oligo(dT)-cellulose chromatography.
- In vitro translation using a rabbit reticulocyte lysate system followed by SDS-PAGE.
- Sucrose density-gradient centrifugation and Northern blot hybridization with a cDNA probe.
Main Results:
- Messenger RNA for glycine methyltransferase was preferentially associated with free polysomes.
- A 1000-fold purification of GMT mRNA was achieved, yielding nearly homogeneous mRNA.
- In vitro translation produced a single major protein band corresponding to the GMT subunit, indicating no precursor form.
- The GMT mRNA was estimated to contain approximately 1,300 nucleotides.
Conclusions:
- The study successfully isolated and purified rat liver glycine methyltransferase mRNA.
- The findings suggest that glycine methyltransferase is synthesized as a mature subunit without a precursor form.
- The characterization of GMT mRNA provides insights into the molecular mechanisms of enzyme synthesis and regulation.