Two forms of rat brain glutamic acid decarboxylase differ in their dependence on free pyridoxal phosphate

Larry Denner, J. Y. Wu

Research output: Contribution to journalArticle

81 Citations (Scopus)

Abstract

There are two forms of glutamate decarboxylase (GAD) found in the rat brain. One form (form A) does not require exogenous pyridoxal-5'-phosphate (PLP) for activity whereas another form (form B) requires exogenous PLP for activity. These two forms differ greatly in temperature sensitivity, inactivation, and reactivation by the removal and readdition of PLP, electrophoretic mobility, and regional distribution. For instance, forms A and B are inactivated to an extent of 91% and 10%, respectively, by the treatment at 45°C for 30 min; form A is greatly inactivated (77%) by the removal of PLP by aminooxyacetic acid and the readdition of PLP, whereas form B is only slightly inactivated (7%). Forms A and B can be clearly separated by 5% polyacrylamide gel electrophoresis in which form A migrates faster than form B. In all 10 brain regions studied, form A is present in smaller amounts than form B. This difference is greatest in the superior colliculus (the ratio of B to A is about 5), while in the locus coeruleus and cerebellum, forms A and B are present in nearly equal proportion. Forms A and B are similar with respect to relative abundance in hypotonic, isotonic, and hypertonic preparations, inhibition of catalytic activity by a carbonyl-trapping agent, immunochemical properties, and chromatographic patterns in a variety of systems. The significance of forms A and B and PLP in the regulation of γ-aminobutyric acid (GABA) level is also discussed.

Original languageEnglish (US)
Pages (from-to)957-965
Number of pages9
JournalJournal of Neurochemistry
Volume44
Issue number3
StatePublished - 1985
Externally publishedYes

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Pyridoxal Phosphate
Glutamate Decarboxylase
Rats
Brain
Aminooxyacetic Acid
Aminobutyrates
Electrophoretic mobility
Locus Coeruleus
Superior Colliculi
Electrophoresis
Cerebellum
gamma-Aminobutyric Acid
Polyacrylamide Gel Electrophoresis
Catalyst activity
Temperature

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

Cite this

Two forms of rat brain glutamic acid decarboxylase differ in their dependence on free pyridoxal phosphate. / Denner, Larry; Wu, J. Y.

In: Journal of Neurochemistry, Vol. 44, No. 3, 1985, p. 957-965.

Research output: Contribution to journalArticle

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