User talk:Bigrocksmall/sandbox

glutamate decarboxylase Identifiers EC number 4.1.1.15 CAS number 9024-58-2m Databases IntEnz IntEnz view BRENDA BRENDA entry ExPASy NiceZyme view KEGG KEGG entry MetaCyc metabolic pathway PRIAM profile PDB structures RCSB PDB PDBe PDBsum Gene Ontology AmiGO / QuickGO Search Glutamic acid decarboxylase 1 PDB GAD67.jpg GAD67 derived from PDB: 2okj​ Identifiers Symbol GAD1 Alt. symbols glutamate decarboxylase 1 (brain, 67kD); GAD67 Entrez 2571 HUGO 4092 OMIM 605363 RefSeq NM_000817 UniProt Q99259 Other data EC number 4.1.1.15 Locus Chr. 2 q31 glutamic acid decarboxylase 2 Identifiers Symbol GAD2 Alt. symbols GAD65 Entrez 2572 HUGO 11284 OMIM 4093 RefSeq NM_001047 UniProt Q05329 Other data EC number 4.1.1.15 Locus Chr. 10 p11.23 Glutamate decarboxylase or glutamic acid decarboxylase (GAD) is an enzyme that catalyzes the decarboxylation of glutamate to GABA and CO2. GAD uses PLP as a cofactor. The reaction proceeds as follows:

HOOC-CH2-CH2-CH(NH2)-COOH → CO2 + HOOC-CH2-CH2-CH2NH2 In mammals, GAD exists in two isoforms with molecular weights of 67 and 65 kDa (GAD67 and GAD65), which are encoded by two different genes on different chromosomes (GAD1 and GAD2 genes, respectively).[1] GAD67 and GAD65 are expressed in the brain where GABA is used as a neurotransmitter, and they are also expressed in the insulin-producing β-cells of the pancreas, in varying ratios depending upon the species.[2]

Several truncated transcripts and polypeptides of GAD67 are detectable in the developing brain,[3] however their function, if any, is unknown.

Contents 1 Regulation of GAD65 and GAD67 2 Role in pathology 2.1 Diabetes 2.2 Stiff person syndrome 2.3 Schizophrenia and bipolar disorder 2.4 Parkinson disease 2.5 Cerebellar disorders 2.6 Neuropathic pain 3 Other Anti-GAD-associated neurologic disorders 4 References 5 External links Regulation of GAD65 and GAD67 GAD65 and GAD67 synthesize GABA at different locations in the cell, at different developmental times, and for functionally different purposes.[4][5] GAD67 is spread evenly throughout the cell while GAD65 is localized to nerve terminals.[4][6][7] This difference is thought to reflect a functional difference; GAD67 synthesizes GABA for neuron activity unrelated to neurotransmission, such as synaptogenesis and protection from neural injury.[4][5] This function requires widespread, ubiquitous presence of GABA. GAD65, however, synthesizes GABA for neurotransmission,[4] and therefore is only necessary at nerve terminals and synapses. In order to aid in neurotransmission, GAD65 forms a complex with Heat Shock Cognate 70 (HSC70), cysteine string protein (CSP) and Vesicular GABA transporter VGAT, which, as a complex, helps package GABA into vesicles for release during neurotransmission.[8] GAD67 is transcribed during early development, while GAD65 is not transcribed until later in life.[4] This developmental difference in GAD67 and GAD65 reflects the functional properties of each isoform; GAD67 is needed throughout development for normal cellular functioning, while GAD65 is not needed until slightly later in development when synaptic inhibition is more prevalent.[4]

GAD67 and GAD65 are also regulated differently post-translationally. Both GAD65 and GAD67 are regulated via phosphorylation,[9] but the regulation of these isoforms differs; GAD65 is activated by phosphorylation while GAD67 is inhibited by phosphorylation. GAD67 is phosphorylated at threonine 91 by protein kinase A (PKA), while GAD65 is phosphorylated, and therefore regulated by, protein kinase C (PKC). Both GAD67 and GAD65 are also regulated post-translationally by Pyridoxal 5’-phosphate (PLP); GAD is activated when bound to PLP and inactive when not bound to PLP.[10] Majority of GAD67 is bound to PLP at any given time, whereas GAD65 binds PLP when GABA is needed for neurotransmission.[10] This reflects the functional properties of the two isoforms; GAD67 must be active at all times for normal cellular functioning, and is therefore constantly activated by PLP, while GAD65 must only be activated when GABA neurotransmission occurs, and is therefore regulated according to the synaptic environment.

Role in pathology Diabetes Both GAD67 and GAD65 are targets of autoantibodies in people who later develop type 1 diabetes mellitus or latent autoimmune diabetes.[11][12] Injections with GAD65 in ways that induce immune tolerance have been shown to prevent type 1 diabetes in rodent models.[13][14][15] In clinical trials, injections with GAD65 have been shown to preserve some insulin production for 30 months in humans with type 1 diabetes.[16][17]

Stiff person syndrome High titers of autoantibodies to glutamic acid decarboxylase (GAD) are well documented in association with stiff person syndrome (SPS). Glutamic acid decarboxylase is the rate-limiting enzyme in the synthesis of γ-aminobutyric acid (GABA), and impaired function of GABAergic neurons has been implicated in the pathogenesis of SPS. Autoantibodies to GAD might be the causative agent or a disease marker.[18]

Schizophrenia and bipolar disorder Substantial dysregulation of GAD mRNA expression, coupled with downregulation of reelin, is observed in schizophrenia and bipolar disorder.[19] The most pronounced downregulation of GAD67 was found in hippocampal stratum oriens layer in both disorders and in other layers and structures of hippocampus with varying degrees.[20]

GAD67 is a key enzyme involved in the synthesis of inhibitory neurotransmitter GABA and people with schizophrenia have been shown to express lower amounts of GAD67 in the dorsolateral prefrontal cortex compared to healthy controls.[21] The mechanism underlying the decreased levels of GAD67 in people with schizophrenia remains unclear. Some have proposed that an immediate early gene, Zif268, which normally binds to the promoter region of GAD67 and increases transcription of GAD67, is lower in schizophrenic patients, thus contributing to decreased levels of GAD67.[21] Since the dorsolateral prefrontal cortex (DLPFC) is involved in working memory, and GAD67 and Zif268 mRNA levels are lower in the DLPFC of schizophrenic patients, this molecular alteration may account, at least in part, for the working memory impairments associated with the disease.

Parkinson disease The bilateral delivery of glutamic acid decarboxylase (GAD) by an adeno-associated viral vector into the subthalamic nucleus of patients between 30 and 75 years of age with advanced, progressive, levodopa-responsive Parkinson disease resulted in significant improvement over baseline during the course of a six-month study.[22]

Cerebellar disorders Intracerebellar administration of GAD autoantibodies to animals increases the excitability of motoneurons and impairs the production of nitric oxide (NO), a molecule involved in learning. Epitope recognition contributes to cerebellar involvement.[23] Reduced GABA levels increase glutamate levels as a consequence of lower inhibition of subtypes of GABA receptors. Higher glutamate levels activate microglia and activation of xc(−) increases the extracellular glutamate release.[24]

Neuropathic pain Peripheral nerve injury of the sciatic nerve (a neuropathic pain model) induces a transient loss of GAD65 immunoreactive terminals in the spinal cord dorsal horn and suggests a potential involvement for these alterations in the development and amelioration of pain behaviour.[25]

Other Anti-GAD-associated neurologic disorders Antibodies directed against glutamic acid decarboxylase (GAD) are increasingly found in patients with other symptoms indicative of central nervous system (CNS) dysfunction, such as ataxia, progressive encephalomyelitis with rigidity and myoclonus (PERM), limbic encephalitis, and epilepsy.[26] The pattern of anti-GAD antibodies in epilepsy differs from type 1 diabetes and stiff-person syndrome.[27]

Your section on plants is good, however it left me wondering how they were administering the glutamate decarboxylase to the plants. Do they already have it because it plays a role in citrate metabolism or is it something that they add to the plants and if so how do they add it? It also looks like your article that you cite here only deals with citrus. Have you found any evidence of it being used in any other type of fruit or vegetable? If not, it would be good to make sure that this is a use of glutamate decarboxylase specific to citrus. It might be good to retitle that section accordingly, unless there are other ways that glutamate decarboxylase is relevant to plants. I like your addition to the intro, as well as your two images as I feel that they add quite a bit to the article. My only other suggestions thus far is that I don't know that all of the text on your talk page should be here, it probably should go on your sandbox main page. If you need another place to put it, I believe you can make another sandbox (it talked about it on one of the tutorials). But overall great job so far! Emandems1 (talk) 20:54, 24 November 2018 (UTC)

I agree with user Emandems1, your figures are a good addition. However, I fear your edits might be difficult to incorporate into the new page without cutting and pasting the entire thing, which we should avoid. ApexofAdharma (talk) 03:12, 4 December 2018 (UTC)