Characterisation of cAMP-dependent protein kinase isoforms in the brain of the crab Chasmagnathus |
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Authors: | F Locatelli C LaFourcade H Maldonado A Romano |
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Institution: | (1) Laboratorio de Neurobiología de la Memoria, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab II (1428) Buenos Aires, Argentina e-mail: aromano@bg.fcen.uba.ar Fax: +54-11-45763321, AR |
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Abstract: | In the crab Chasmagnathus learning model, systemic administration of cAMP analogues that are specific activators or inhibitors of cAMP-dependent protein
kinase (PKA) proved to respectively facilitate or impair long-term retention. The aims of the present work were to analyse
PKA activity distribution in the crab brain and to characterise PKA isoforms. The neuropils from the eyestalk showed higher
levels of induced PKA activity when compared with other neuropils of the central nervous system. Two PKA isoforms, homologous
to mammalian PKA I and PKA II, were detected from central brain protein extracts using DEAE chromatography. Only PKA II was
found in lateral protocerebrum extracts, suggesting a role of this isoform in the processing of visual inputs and in the integration
of this information with other sensory inputs. PKA I was observed to be ten-fold more sensitive to cAMP than PKA II. cGMP
induced a high activation of both PKA isoforms, similar to that obtained with cAMP. PKA I showed a two-fold greater sensitivity
for cGMP than PKA II. An autophosphorylation assay was performed and a protein of 55 kDa, corresponding to phosphorylated
R II regulatory subunit, was detected. The presence of a PKA I isoform with high sensitivity for cAMP in the central brain
suggests a role of this subtype in long-term memory.
Accepted: 29 August 2000 |
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Keywords: | PKA isoforms PKA autophosphorylation cAMP and cGMP Crab brain Memory |
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