Stimulation of hypothalamic histidine decarboxylase by calcium-calmodulin and protein kinase (cAMP-dependent) inhibitor

Z. Huszti, K. Magyar

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Stimulatory effects of Ca2+-CaM* and PKI on partially purified hypothalamic HD (10 fold purification) have been shown under conditions involving inhibition of the enzyme by cAMP-induced phosphorylation and under control conditions. A 1:1 (v/v) mixture of 0.1 m M CaCl2 and 10 units of CaM from human red blood cells reversed the inhibition of HD induced by cAMP-dependent protein phosphorylation activity to the control level. Verapamil (0.01 m M) could partially block the former effect without affecting the control level of enzyme activity. 0.01 m M TPA did not further increase the effect of Ca2+-CaM on HD, in the presence of 0.01 m M ATP, indicating that this stimulation does not require the action of Ca2+-dependent protein kinase. The control level of HD is not influenced by 0.1 m M CaCl2 or 0.02 m M EGTA but is raised by CaM in the presence of CaCl2 (0.1 m M). A highly purified protein kinase (cAMP-dependent) inhibitor (PKI) from bovine heart and a crude inhibitor from rat cerebellum could also reverse the inhibitory effect of cAMP-dependent protein kinase under phosphorylating conditions and enhanced HD activity above control levels. PKI and Ca2+-CaM, added together, produced single, not additive effects. We conclude that cAMP-induced phosphorylation is probable the main regulatory mechanism of histamine formation and this could be influenced by both Ca2+-CaM and PKI. Inhibition of cAMP-dependent protein kinase as well as stimulation of phosphoprotein phosphatase and Ca2+-CaM-dependent phosphodiesterase might be involved in the above actions.

Original languageEnglish
Pages (from-to)233-235
Number of pages3
JournalAgents and Actions
Volume20
Issue number3-4
DOIs
Publication statusPublished - Apr 1987

Fingerprint

Histidine Decarboxylase
Calcium-Calmodulin-Dependent Protein Kinases
Level control
Cyclic AMP-Dependent Protein Kinases
Protein Kinases
Phosphorylation
Calcium
Phosphoprotein Phosphatases
Egtazic Acid
Phosphoric Diester Hydrolases
Enzymes
Verapamil
Cerebellum
Histamine
Enzyme activity
Adenosine Triphosphate
Erythrocytes
Purification
Rats
Blood

ASJC Scopus subject areas

  • Toxicology
  • Pharmacology (medical)

Cite this

Stimulation of hypothalamic histidine decarboxylase by calcium-calmodulin and protein kinase (cAMP-dependent) inhibitor. / Huszti, Z.; Magyar, K.

In: Agents and Actions, Vol. 20, No. 3-4, 04.1987, p. 233-235.

Research output: Contribution to journalArticle

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