A novel splicing variant encoding putative catalytic α subunit of maize protein kinase CK2
| Autor: | Maja Łebska, Grażyna Dobrowolska, Stefano Moro, Giorgio Cozza, Jadwiga Szczegielniak, Grażyna Muszyńska |
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| Rok vydání: | 2009 |
| Předmět: |
Models
Molecular DNA Complementary Physiology Sequence analysis Protein subunit Molecular Sequence Data Plant Science Biology medicine.disease_cause Zea mays Catalytic Domain Complementary DNA Genetics medicine Amino Acid Sequence Cloning Molecular Phosphorylation Casein Kinase II Protein kinase A Gene Escherichia coli chemistry.chemical_classification Caseins Cell Biology General Medicine Molecular biology Isoenzymes Enzyme chemistry Biochemistry RNA Plant RNA splicing Sequence Alignment |
| Zdroj: | Physiologia Plantarum. 136:251-263 |
| ISSN: | 1399-3054 0031-9317 |
| Popis: | A cDNA highly homologous to the known catalytic alpha subunit of protein kinase CK2 was cloned from maize (Zea mays). It was designated ZmCK2alpha-4 (accession no. AAF76187). Sequence analysis shows that ZmCK2alpha-4 and the previously identified ZmCK2alpha-1 (accession no. X61387) are transcribed from the same gene, ZmPKCK2AL (accession no. Y11649), but at different levels in various maize organs and at different stages of development. The cDNA encoding ZmCK2alpha-4 has three potential translation initiation sites. The three putative variants of ZmCK2alpha-4 were expressed in Escherichia coli as GST-fusion proteins and purified from bacterial extracts. In contrast to the previously characterized ZmCK2alphas, the obtained GST:ZmCK2alpha-4 proteins were catalytically inactive as monomers or in the presence of equimolar amounts of the human CK2beta. However, GST:ZmCK2alpha-4 did phosphorylate casein in the presence of a large excess of the beta subunit. The activity of ZmCK2alpha-4 toward casein could also be stimulated by increasing ATP concentration. Modeling studies have shown that there is no interaction between the N-terminal segment of ZmCK2alpha-4 and the activation loop responsible for constitutive catalytic activity of CK2alpha. Preliminary results suggest that ZmCK2alpha-4 may function as a negative regulator of other CK2s, and at certain circumstances as a holoenzyme which catalytic activity is stimulated by specific regulatory subunit(s). |
| Databáze: | OpenAIRE |
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