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Ergopeptine‐Sensitive Calcium‐Dependent Protein Phosphorylation System in the Brain
Author(s) -
Stratford Carol A.,
Fisher Stephen K.,
Ueda Tetsufumi
Publication year - 1984
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 - 10.1111/j.1471-4159.1984.tb02758.x
Subject(s) - bromocriptine , phosphorylation , calmodulin , protein phosphorylation , calcium , chemistry , dopamine , microbiology and biotechnology , biochemistry , threonine , hippocampus , biology , protein kinase a , neuroscience , serine , enzyme , hormone , organic chemistry , prolactin
We studied a protein phosphorylation system that is regulated by the dopamine‐mimetic ergot bromocriptine. Bromocriptine was found to inhibit selectively the endogenous phosphorylation of a threonine residue(s) in 50,000‐ and 60,000‐dalton proteins in a synaptosome fraction. The bromocriptine‐sensitive phosphorylation is stimulated by calcium and by calmodulin, and occurs predominantly in the brain. The inhibitory effect of bromocriptine was not mimicked by 3,4‐dihydroxyphenylethylamine or by any of the neurotransmitters and related agents tested, but was mimicked, although less effectively, by other ergots that contain peptide moieties. In the hippocampus, the brain region with the highest content of the 50,000‐ and 60,000‐dalton proteins, the ergopeptine‐sensitive protein phosphorylation appears to be localized to interneurons or cell bodies whose axons synapse outside the hippocampus. The results raise the possibility that some of the bromocriptine‐ and ergopeptine‐induced pharmacological effects in the CNS may be mediated by the inhibition of the calcium/calmodulin‐dependent phosphorylation of these specific proteins.