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The Synthesis of Acetylcholine by Human Erythrocytes1 William C

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Acetylcholine Synthesis Pathway Made Simple - YouTube

N2 - In order to clarify the origin of acetylcholine (ACh) in human blood, we measured the content and synthesis activity of ACh in several human leukemic cell lines. The intracellular ACh content determined by a specific and sensitive radioimmunoassay in the human leukemic T cell lines, HSB-2, MOLT- 3, and CEM, was 79.6, 36.2, and 9.5 pmol/106 cells, respectively. These values were 9-70-fold higher than those of other cell lines, including a helper T cell line, Jurkat. Stimulation of HSB-2 and MOLT-3 by phytohemagglutinin (PHA) increased both the intracellular content and release of ACh into the culture medium, but did not influence the intracellular content and release of ACh in CEM. ACh synthesis activity was found in all the T cell lines tested. Bromoacetylcholine (100 μM), a choline acetyltransferase (CHAT) inhibitor, and bromoacetyl-L-carnitine (100 μM), a carnitine acetyltransferase (CarAT) inhibitor, decreased ACh-synthesizing activity in MOLT-3, and HSB-2 and CEM, by about 50% and 30%, respectively, indicating that both CHAT, and to a lesser extent CarAT, are involved in ACh synthesis in T cells. These results suggest that T lymphocytes have the potential to synthesize and release ACh, which may play a role in regulating T cell-dependent immune responses.

T1 - Localization and synthesis of acetylcholine in human leukemic T cell lines

Like the vesicular acetylcholine transporter, the plasma membrane choline transporter was first cloned and characterized in (). The ChT protein () is a member of a class of sodium-dependent transporters with substrates such as glucose (SGLT1) and inositol (SMIT1). It is best modeled as a 13-transmembrane domain protein, with a short N-terminus oriented extracellularly, and an extended, C-terminus oriented into the cytoplasm (; ). Assays performed in embryonic cell culture showed that the transporter was sodium- and chloride-dependent, with an apparent Km for choline of 0.66 M, comparable to mammalian transporters ().

Synthesis, Storage and Release of Acetylcholine - …

The reference allele, , is a precise 1695 bp deletion which eliminates more than half of the coding sequence; it is almost certainly a null allele. Animals homozygous for are viable, and their growth and development appear to be normal. However, although mutants have little difficulty crawling on agar, they swim somewhat more slowly that wild-type animals, and become paralyzed (“fatigued”) more quickly than wild-type animals during prolonged swimming in liquid (). It is tempting to speculate that there is enough endogenous choline and/or low-affinity choline uptake activity (see below) in the mutant nerve terminals to support some ACh synthesis even without any high-affinity reuptake activity, and that this level of ACh synthesis is sufficient for locomotion in a calm environment. However, this level of ACh is not adequate to support the increased demands of vigorous swimming, and the motor neurons appear to become depleted of transmitter. This provides genetic-based evidence for a functional coupling of choline transport and ACh synthesis, and supports previous models based on other methods (; ; ).

If choline is indeed rate-limiting for acetylcholine synthesis under some circumstances, what determines the availability of choline? In , choline is synthesized in the form of phosphocholine through progressive N-methylation of phosphoethanolamine by the and methyltransferases (). Choline may also be produced through cleavage of phosphatidylcholine by phospholipase D (). Choline is thus a product of lipid metabolism and lipid turnover. The activities of these enzymes have not been analyzed in cholinergic neurons.

The Synthesis of Acetylcholine - ResearchGate

Genetic and molecular studies showed that and were part of a complex gene locus and transcription unit, with the gene nested in the long first intron of (see ; ; ). Thus, the sequential steps of acetylcholine synthesis and vesicle-loading are encoded by different genes within a single, complex transcription unit. Subsequent studies demonstrated that a similar nested structure of these genes is present in mammals and insects (; ). This is now commonly called the cholinergic gene locus, or CGL, and is present in all metazoans thus far examined (). It is noteworthy that the genes encoding enzymes and transporters for other neurotransmitters are not organized in a comparable way.

is a post-synaptic choline/acetylcholine transporter (). It is a member of the family of plasma membrane transporters which includes the serotonin transporter (), the dopamine transporter (), and the GABA transporter (). The only two substrates identified for were choline and acetylcholine; both substrates had comparable Km values, but the Vmax for choline was about seven times the Vmax for acetylcholine (). This appears to be a nematode-specific transport activity. The protein is expressed in muscles, and is preferentially localized to neuromuscular junctions. mutants are somewhat uncoordinated and mildly hypersensitive to aldicarb. This transport activity may provide a mechanism for rapid clearance of synaptic ACh and/or choline during periods of high transmitter release.

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acetylcholine synthesis:- choline acetyltransferase activity

The vesicular acetylcholine transporter was first cloned and characterized in (), where it was shown to be the product of the gene. Structurally, the (VAChT) protein has 12 transmembrane domains, with cytoplasmic (i.e., extravesicular) N- and C-termini, and is closely related to the vesicular monoamine transporters (VMATs). Immunoreactivity with anti-UNC-17 antibody preparations in wild-type animals is punctate and colocalizes with the synaptic vesicle protein synaptotagmin, suggesting that is associated with synaptic vesicles (). This punctate staining is mislocalized in mutants, providing additional support to the conclusion that is an integral membrane protein of synaptic vesicles.

This uptake can be blocked by hemicholinium

Department of Pharmacology and Clinical Pharmacology, Uludag University Medical School, Bursa, Turkey.
Treatments that increase acetylcholine release from brain slices decrease the synthesis of phosphatidylcholine by, and its levels in, the slices.

acetylcholine - neurosciencenotes - Google Sites

As shown in , ACh is synthesized by choline acetyltransferase (ChAT), and is loaded into synaptic vesicles by the vesicular acetylcholine transporter (VAChT). The synaptic vesicle lumen is acidified by the action of an ATP-dependent proton pump located in the synaptic vesicle membrane. The pH gradient between the vesicle lumen and the cytoplasm provides the driving force for ACh transport; the VAChT essentially “exchanges” ACh for protons. The docking and priming of synaptic vesicles, and their calcium-stimulated fusion with the cell membrane are all general processes that are independent of the neurotransmitter contained in the vesicles (and are described elsewhere in this volume). Following synaptic vesicle fusion and transmitter release, the ACh diffuses within the synaptic cleft and activates acetylcholine receptors (AChRs), usually located on post-synaptic cells. For most other neurotransmitters (e.g., GABA, dopamine, serotonin), the action of the transmitter is terminated by transporter- mediated removal of the transmitter from the synaptic cleft. The action of acetylcholine, however, is terminated by direct enzymatic hydrolysis of the neurotransmitter in the synaptic cleft by acetylcholinesterase (AChE). The resulting choline is then transported back into the presynaptic neuron by a high affinity choline transporter (HAChT, or ChT); this choline is then available for the synthesis of additional ACh.

Lookup the document at: Acetylcholine synthesis by pChAT in DRG

In order to clarify the origin of acetylcholine (ACh) in human blood, we measured the content and synthesis activity of ACh in several human leukemic cell lines. The intracellular ACh content determined by a specific and sensitive radioimmunoassay in the human leukemic T cell lines, HSB-2, MOLT- 3, and CEM, was 79.6, 36.2, and 9.5 pmol/106 cells, respectively. These values were 9-70-fold higher than those of other cell lines, including a helper T cell line, Jurkat. Stimulation of HSB-2 and MOLT-3 by phytohemagglutinin (PHA) increased both the intracellular content and release of ACh into the culture medium, but did not influence the intracellular content and release of ACh in CEM. ACh synthesis activity was found in all the T cell lines tested. Bromoacetylcholine (100 μM), a choline acetyltransferase (CHAT) inhibitor, and bromoacetyl-L-carnitine (100 μM), a carnitine acetyltransferase (CarAT) inhibitor, decreased ACh-synthesizing activity in MOLT-3, and HSB-2 and CEM, by about 50% and 30%, respectively, indicating that both CHAT, and to a lesser extent CarAT, are involved in ACh synthesis in T cells. These results suggest that T lymphocytes have the potential to synthesize and release ACh, which may play a role in regulating T cell-dependent immune responses.

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