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Poly(adenylate) polymerase activity of rat brain
Journal of Neurochemistry
|April 1, 1982
Summary
Rat brain poly(adenylate) polymerase, an enzyme crucial for RNA processing, exists in two forms. These forms exhibit distinct kinetic properties and varying sensitivities to inhibitors, impacting their function in nuclear processes.
Area of Science:
- Biochemistry
- Molecular Biology
- Neuroscience
Background:
- Poly(adenylate) [poly(A)] polymerase is essential for mRNA processing.
- This enzyme's properties can vary depending on its cellular location and preparation method.
Purpose of the Study:
- To characterize the poly(adenylate) polymerase from rat brain nuclei.
- To compare the properties of two distinct forms of the enzyme released from nuclei.
Main Methods:
- Nuclei were isolated from rat brain and subjected to different buffer conditions (hypertonic, hypotonic) to release the enzyme.
- Enzyme activity was assayed under varying conditions of manganese (Mn), pH, ATP, and poly(A) primer concentrations.
- Kinetic properties and responses to various effectors (calcium, cyclic nucleotides, polyamines, pyrophosphate, GTP) were evaluated for both enzyme forms.
Main Results:
- Two forms of poly(adenylate) polymerase (Form I and Form II) were isolated from rat brain nuclei.
- Form I, released by gentle incubation, showed specific optima for Mn, pH, and ATP, with a high poly(A) primer requirement.
- Form II, released by homogenization, exhibited linear kinetics and slight stimulation by cyclic nucleotides, while both forms were inhibited by polyamines and pyrophosphate.
Conclusions:
- Rat brain poly(adenylate) polymerase exists in at least two distinct molecular forms with differential biochemical properties.
- These forms may play unique roles in nuclear RNA processing, influenced by their preparation method and regulatory factors.