PMID- 10446215
OWN - NLM
STAT- MEDLINE
DCOM- 19990909
LR  - 20210209
IS  - 0021-9258 (Print)
IS  - 0021-9258 (Linking)
VI  - 274
IP  - 34
DP  - 1999 Aug 20
TI  - Role of synaptic vesicle proton gradient and protein phosphorylation on 
      ATP-mediated activation of membrane-associated brain glutamate decarboxylase.
PG  - 24366-71
AB  - Previously, we have shown that the soluble form of brain glutamic acid 
      decarboxylase (GAD) is inhibited by ATP through protein phosphorylation and is 
      activated by calcineurin-mediated protein dephosphorylation (Bao, J., Cheung, W. 
      Y., and Wu, J. Y. (1995) J. Biol. Chem. 270, 6464-6467). Here we report that the 
      membrane-associated form of GAD (MGAD) is greatly activated by ATP, whereas 
      adenosine 5'-[beta,gamma-imido]triphosphate (AMP-PNP), a non-hydrolyzable ATP 
      analog, has no effect on MGAD activity. ATP activation of MGAD is abolished by 
      conditions that disrupt the proton gradient of synaptic vesicles, e.g. the 
      presence of vesicular proton pump inhibitor, bafilomycin A1, the protonophore 
      carbonyl cyanide m-chorophenylhydrazone or the ionophore gramicidin, indicating 
      that the synaptic vesicle proton gradient is essential in ATP activation of MGAD. 
      Furthermore, direct incorporation of (32)P from [gamma-(32)P]ATP into MGAD has 
      been demonstrated. In addition, MGAD (presumably GAD65, since it is recognized by 
      specific monoclonal antibody, GAD6, as well as specific anti-GAD65) has been 
      reported to be associated with synaptic vesicles. Based on these results, a model 
      linking gamma-aminobutyric acid (GABA) synthesis by MGAD to GABA packaging into 
      synaptic vesicles by proton gradient-mediated GABA transport is presented. 
      Activation of MGAD by phosphorylation appears to be mediated by a vesicular 
      protein kinase that is controlled by the vesicular proton gradient.
FAU - Hsu, C C
AU  - Hsu CC
AD  - Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 
      66045, USA.
FAU - Thomas, C
AU  - Thomas C
FAU - Chen, W
AU  - Chen W
FAU - Davis, K M
AU  - Davis KM
FAU - Foos, T
AU  - Foos T
FAU - Chen, J L
AU  - Chen JL
FAU - Wu, E
AU  - Wu E
FAU - Floor, E
AU  - Floor E
FAU - Schloss, J V
AU  - Schloss JV
FAU - Wu, J Y
AU  - Wu JY
LA  - eng
PT  - Journal Article
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PL  - United States
TA  - J Biol Chem
JT  - The Journal of biological chemistry
JID - 2985121R
RN  - 0 (Protons)
RN  - 555-60-2 (Carbonyl Cyanide m-Chlorophenyl Hydrazone)
RN  - 56-12-2 (gamma-Aminobutyric Acid)
RN  - 8L70Q75FXE (Adenosine Triphosphate)
RN  - EC 4.1.1.15 (Glutamate Decarboxylase)
SB  - IM
MH  - Adenosine Triphosphate/*physiology
MH  - Animals
MH  - Biological Transport
MH  - Brain/*enzymology
MH  - Carbonyl Cyanide m-Chlorophenyl Hydrazone/pharmacology
MH  - Cell Membrane/enzymology
MH  - Diabetes Mellitus, Type 1/blood
MH  - Enzyme Activation
MH  - Glutamate Decarboxylase/*metabolism
MH  - Humans
MH  - Protons
MH  - Rabbits
MH  - Swine
MH  - Synaptic Vesicles/*metabolism
MH  - gamma-Aminobutyric Acid/metabolism
EDAT- 1999/08/14 00:00
MHDA- 1999/08/14 00:01
CRDT- 1999/08/14 00:00
PHST- 1999/08/14 00:00 [pubmed]
PHST- 1999/08/14 00:01 [medline]
PHST- 1999/08/14 00:00 [entrez]
AID - S0021-9258(19)55568-5 [pii]
AID - 10.1074/jbc.274.34.24366 [doi]
PST - ppublish
SO  - J Biol Chem. 1999 Aug 20;274(34):24366-71. doi: 10.1074/jbc.274.34.24366.