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Adenosine(5')tetraphospho(5')adenosine-binding protein of calf thymus
European Journal of Biochemistry
|January 2, 1984
Summary
Researchers purified an adenosine(5)tetraphospho(5)adenosine (Ap4A) binding protein from calf thymus. This protein specifically binds Ap4A and shows a distinct association with DNA polymerase alpha.
Area of Science:
- Molecular Biology
- Enzymology
- Biochemistry
Background:
- Adenosine(5')tetraphospho(5')adenosine (Ap4A) is a dinucleotide signaling molecule.
- Understanding proteins that interact with Ap4A is crucial for cellular processes.
Purpose of the Study:
- To purify and characterize an Ap4A binding protein from calf thymus.
- To investigate the relationship between the Ap4A binding protein and DNA polymerase alpha.
Main Methods:
- Protein purification using affinity chromatography.
- Characterization of protein binding affinity and substrate specificity.
- Enzyme activity assays for phosphohydrolase activity.
- Analysis of protein association with DNA polymerase alpha.
Main Results:
- An Ap4A binding protein (Mr 54000) was purified, exhibiting high-affinity and specific binding to Ap4A.
- Two forms were identified: a predominant free form with Ap4Aase activity and a form copurifying with DNA polymerase alpha, lacking Ap4Aase activity.
- Zinc ions (Zn2+) inhibited Ap4Aase activity but not Ap4A binding.
Conclusions:
- The Ap4A binding protein specifically interacts with Ap4A.
- A distinct association exists between the Ap4A binding protein and DNA polymerase alpha.
- The differential Ap4Aase activity suggests functional regulation in the polymerase-bound form.