Neurotransmitters glycine

Steeves, C.L. et al., 2003, The glycine neurotransmitter transporter GLYT1 is an organic osmolyte transporter regulating cell volume in cleavage-stage embryos. Proc. Natl. Acad. Sci. TJ.S.A. 100(24) 13982-13987. 

Picrotoxin has been instmmental in estabUshing an inhibitory neurotransmitter role for the amino acid, gamma-aminobutyric acid (GABA), quantitatively the most important inhibitory neurotransmitter in the mammalian CNS. Whereas glycine is predominately localized in the spinal cord, GABA... 

Substrate specificity is determined by high affinity for the cognate neurotransmitter substrate. However, low affinity uptake does also have a part in the clearance of transmitters from the interstitial space (e.g., in uptake mediated by the extraneuronal monoamine transporter, EMT) and in the intestinal absoiption of glycine and glutamate. It is obvious that there is an evolutionary relation of neurotransmitter transporters and amino acid and cation transporters in epithelia. 

Neurotransmitter turnover differs for the individual neurotransmitters. Glutamate and glycine require... 

Neurotransmitter Transporters. Table 2 SLC6 family transporters for GABA (y-amino butyric acid) and glycine... 

Glycine transporter GlyTl (SLC6A9) CNS-glia -20 Clearance of interstitial neurotransmitter Sarcosine... 

The amino acid glycine, a neurotransmitter at inhibitory synapses throughout the central nervous system (CNS),... 

Synaptic vesicles isolated from brain exhibit four distinct vesicular neurotransmitter transport activities one for monoamines, a second for acetylcholine, a third for the inhibitory neurotransmitters GABA and glycine, and a fourth for glutamate [1], Unlike Na+-dependent plasma membrane transporters, the vesicular activities couple to a proton electrochemical gradient (A. lh+) across the vesicle membrane generated by the vacuolar H+-ATPase ( vacuolar type proton translocating ATPase). Although all of the vesicular transport systems rely on ApH+, the relative dependence on the chemical and electrical components varies (Fig. 1). The... 

By far the most important amino acids are the a-amino acids, in which the —NH2 group is attached to the carbon atom next to the carboxyl group, as in glycine. However, other types of amino acids are common and play an important biological role. For instance, the y-amino acid NH2CH2CH2CH2COOH is the neurotransmitter GABA. 

Glycine is the simplest of all amino acids. It is involved in many metabolic pathways, is an essential component of proteins, and is found throughout the brain. A neurotransmitter role for glycine was first identified in the spinal cord, where it was found to be differentially distributed between dorsal and ventral regions and shown to cause hyperpolarisation of motoneurons (Werman et al. 1967). This inhibitory action of glycine is distinct from its... 

Lamina II is also known as the substantia gelatinosa (SG) and can be divided into two layers, the outer layer (IIo) and the inner layer (Ili). This layer is densely packed with small neurons and lacks myelinated axons. Neurons with cell bodies in Hi receive inputs from low-threshold mechanoreceptive primary afferents, while those in IIo respond to inputs from high-threshold and thermoreceptive afferents. The intrinsic cells which comprise the SG are predominantly stalk and islet cells. Stalk cells are found located in lamina IIo, particularly on the border of lamina I, and most of their axons have ramifications in lamina I although some also project to deeper layers. These cells are thought to predominantly relay excitatory transmission. Islet cells, on the other hand, are located in Hi and have been demonstrated to contain the inhibitory neurotransmitters, y-aminobutyric acid (GABA), glycine and enkephalins in their dendrites. Hence these cells have been proposed to be inhibitory interneurons. 

Amino acid There are 20 different amino acids that provide the building blocks of proteins. Three of them - aspartate, glutamate and glycine (together with GABA, or y-aminobutyric acid) also function as neurotransmitters. 

Neurotransmitter transporters There are probably at least five types of transport protein specific for glutamate, acetylcholine, catecholamines, glycine/GABA and ATP. The type of transporter contributes to determining the transmitter specificity of a synapse. 

An overview of some of the processes involved in synaptic transmission is shown in Figure 10-1. Many of the processes are discussed below or in other chapters of this book. Many different types of substance are neurotransmitters. Classical neurotransmitters, such as ACh (see Ch. 11) and norepinephrine (NE see Ch. 12), are low-molecular-weight substances that have no other function but to serve as neurotransmitters. The predominant excitatory neurotransmitter in the brain, glutamate, and the inhibitory neurotransmitter in the spinal cord, glycine, are common and essential amino acids (see Chs 15 and 16). 

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