Activation of brain tryptophan hydroxylase by ATP-MG2+: dependence on calmodulin.
AUTOR(ES)
Kuhn, D M
RESUMO
Tryptophan hydroxylase [tryptophan 5-monooxygenase, L-tryptophan,tetrahydropterin:oxygen oxidoreductase (5-hydroxylating), EC 1.14.16.4] is activated by phosphorylating conditions (ATP-Mg2+) in a calcium-dependent, cyclic AMP-independent manner. Addition to the phosphorylation reaction of certain antipsychotic drugs that bind to calmodulin, the heat-stable calcium-binding protein, prevents the activation of tryptophan hydroxylase by ATP-Mg2+ in a concentration-dependent fashion. External addition of purified calmodulin protects the enzyme from the drug-induced effects. Calmodulin-free tryptophan hydroxylase prepared by affinity chromatography on fluphenazine-Sepharose is not activated by ATP-Mg2+ whereas addition of calmodulin to calmodulin-free enzyme restores the responsiveness of the hydroxylase to ATP-MG2+ only in the presence of Ca2+. These results indicate that the activation of tryptophan hydroxylase by phosphorylating conditions is dependent on both calcium and calmodulin.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=349911Documentos Relacionados
- Calcium-regulated phosphorylation in synaptosomal cytosol: dependence on calmodulin.
- Saccharomyces cerevisiae protein kinase dependent on Ca2+ and calmodulin.
- Rapid disassembly of cold-stable microtubules by calmodulin.
- Regulation of acetylcholine receptor phosphorylation by calcium and calmodulin.
- The complex ATP–Fe2+ serves as a specific affinity cleavage reagent in ATP-Mg2+ sites of Na,K-ATPase: Altered ligation of Fe2+ (Mg2+) ions accompanies the E1P→E2P conformational change