Calcium effects on the solubilization of membrane-bound histidine decarboxylase in the rat brain.
In a previous work we have shown that histidine decarboxylase (HD) activity is found in a soluble and a membrane-bound form. A major part (82%) of the membrane-bound HD activity in the crude mitochondrial fraction (P2) was present in the synaptic plasma membrane-containing subfraction. Physiological concentrations of Ca2+ had no direct effect on HD activity but caused a solubilization of approximately 50% of membrane-bound HD in the P2 fraction. Mg2+ had similar but lower effects (20% solubilization) than Ca2+. Incubation with depolarizing concentrations of K+ in the presence of 1 mM CaCl2 caused a significant (30%) solubilization of HD.
Toledo
A
A
Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad Autónoma de Barcelona, Spain.
Rodriguez
R
R
Sabriá
J
J
Rodriguez
J
J
Blanco
I
I
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000201:enzymology* / Q000648:ultrastructure; D002118:Calcium / Q000494:pharmacology*; D002458:Cell Fractionation; D002462:Cell Membrane / Q000201:enzymology*; D005260:Female; D006640:Histidine Decarboxylase / Q000378:metabolism*; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012995:Solubility
D011189:Potassium Chloride; D006640:Histidine Decarboxylase; D008274:Magnesium; D002118:Calcium