Isoforms of cAMP-dependent protein kinase in the bivalve mollusk Mytilus galloprovincialis: activation by cyclic nucleotides and effect of temperature
| Autor: | José R. Bardales, J. Antonio Villamarín, Izaskun Ibarguren, María J. Díaz-Enrich |
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| Rok vydání: | 2004 |
| Předmět: |
Gene isoform
Protein subunit Blotting Western Biophysics Activation energy Biology Biochemistry Body Temperature Mole Animals Protein Isoforms Nucleotide Protein kinase A Cyclic GMP Molecular Biology chemistry.chemical_classification Dose-Response Relationship Drug Temperature biology.organism_classification Cyclic AMP-Dependent Protein Kinases Mytilus Arrhenius plot Bivalvia Kinetics chemistry Nucleotides Cyclic |
| Zdroj: | Archives of Biochemistry and Biophysics. 432:71-78 |
| ISSN: | 0003-9861 |
| DOI: | 10.1016/j.abb.2004.09.008 |
| Popis: | Two different isoforms of cAMP-dependent protein kinase (PKA) have been partially purified from the posterior adductor muscle and the mantle tissue of the sea mussel Mytilus galloprovincialis . The holoenzymes contain as regulatory subunit (R) the previously identified isoforms R myt1 and R myt2 , and were named PKA myt1 and PKA myt2 , respectively. Both cAMP and cGMP can activate these PKA isoforms completely, although they exhibit a sensitivity approximately 100-fold higher for cAMP than for cGMP. When compared to PKA myt2 , the affinity of PKA myt1 for cAMP and cGMP is 2- and 3.5-fold higher, respectively. The effect of temperature on the protein kinase activity of both PKA isoforms was examined. Temperature changes did not affect significantly the apparent activation constants ( K a ) for cAMP. However, the protein kinase activity was clearly modified and a remarkable difference was observed between both PKA isoforms. PKA myt1 showed a linear Arrhenius plot over the full range of temperature tested, with an activation energy of 15.3 ± 1.5 kJ/mol. By contrast, PKA myt2 showed a distinct break in the Arrhenius plot at 15 °C; the activation energy when temperature was above 15 °C was 7-fold higher than that of lower temperatures (70.9 ± 8.1 kJ/mol vs 10.6 ± 6.5 kJ/mol). These data indicate that, above 15 °C, PKA myt2 activity is much more temperature-dependent than that of PKA myt1 . This different behavior would be related to the different role that these isoforms may play in the tissues where they are located. |
| Databáze: | OpenAIRE |
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