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Phosphorylation and Activation of Brain Aromatic l ‐Amino Acid Decarboxylase by Cyclic AMP‐Dependent Protein Kinase
Author(s) -
Duchemin AnneMarie,
Berry Mark D,
Neff Norton H,
Hadjiconstantinou Maria
Publication year - 2000
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.2000.0750725.x
Subject(s) - phosphorylation , protein kinase a , biochemistry , biology , protein subunit , enzyme , protein phosphorylation , microbiology and biotechnology , chemistry , gene
Aromatic l ‐amino acid decarboxylase (AAAD), an enzyme required for the synthesis of catecholamines, indoleamines, and trace amines, is rapidly activated by cyclic AMP‐dependent pathways in striatum and midbrain in vivo, suggesting enzyme phosphorylation. We now report that the catalytic subunit of cyclic AMP‐dependent protein kinase (PKA) directly phosphorylated AAAD immunoprecipitated from homogenates prepared from the mouse striatum and midbrain in vitro. Under the same phosphorylation conditions, the catalytic subunit of PKA also phosphorylated a recombinant AAAD protein expressed in Escherichia coli transfected with an AAAD cDNA isolated from the bovine adrenal gland. The PKA‐induced AAAD phosphorylation of immunoprecipitates from striatum and midbrain was time and concentration dependent and blocked by a specific PKA peptide inhibitor. Incubation of the catalytic subunit of PKA with striatal homogenates increased enzyme activity by ~20% in a time‐ and concentration‐dependent manner. Moreover, incubation of the catalytic subunit of PKA with recombinant AAAD increased activity by ~70%. A direct phosphorylation of AAAD protein by PKA might underlie the cyclic AMP‐induced rapid and transient activation of AAAD in vivo.