The Nicotinic Acetylcholine Receptor, Write An Essay Discussing How An

The Nicotinic Acetylcholine Receptor, Write An Essay Discussing How An The Nicotinic Acetylcholine Receptor, Write An Essay Discussing How An Understanding Of Its â€" Essay Example > The nicotinic acetylcholine receptorNicotinic acetylcholine receptors (nAChR) are proteins involved in the cell to cell communication in the nervous system. These are prototypical proteins that are located in the cell membrane that make it possible through the formation of ligand-gated ion channels across the surface of the cells and are responsible for diffusion of signals between cells (Kandel et al, 1995). The intercellular activity of this group of proteins plays a significant role in the brain function of the nervous system of mammals (Crick, 1994). The channels that these receptors formed are ionotropic or affected by ions of charges. Another property is the increase in opening of the neurotransmitter acetylcholine, similar to the muscarinic acetylcholine type, but compared to others this type can be activated by nicotine (Siegel et al. , 1999; Itier and Bertrand, 2001). Being involved in the intercellular communication, these receptors are found in different parts of the bo dy specifically in the central and peripheral nervous system. One of the functions of the nicotinic acetylcholine receptors is in connection with muscle contraction which is controlled by the peripheral nervous system (“Nicotinic acetylcholine receptors”, 2006). The performance of these receptors can be affected by chemical substances such as medicines and abused drugs. An example is the negative effect of cocaine and MK-801 [(+)dizocilpine], a medicine for convulsion to AChR (Hess et al, 2000). Studies of the receptors are being undertaken through the use of cryoelectron microscopy, mutagenesis and labelling. Results show that the structure that is involved in intercellular functions is the five twisted M2 alpha-helices surround a transmembrane (TM) pore (Sansom, 2000). The nicotinic receptors, in particular, have a molecular weight of approximately 280kDa. It belongs to the nicotinicoid receptor family which also has the 5 symmetrical receptor subunits arranged in a pore loc ated in the centre. Members of this group of Cys-loop proteins include GABAA receptors, glycine receptors, and the type 3 serotonin receptors (Cascio, 2004; “Nicotinic acetylcholine receptors”, 2006). The structure of the nicotinic receptor is composed of twelve kinds of subunits with similar hydrophobic regions that form the pentamers, a2 to a10 and ß2 to ß4 (Siegel et al. , 1999; Itier and Bertrand, 2001). Two a subunits, which is a combination of a ß, a d and either a ? or a e comprise the muscle form of nAChR (Siegel et al. , 1999; Itier and Bertrand, 2001; Giniatullin et al. , 2005). On the other hand, the neuronal forms can be composed of different subunits (“Nicotinic acetylcholine receptors”, 2006). When the receptors work a subunits turn more symmetrical as the other subunits and pore approximately 0.65 nm opens. This takes place on the ACh binding site near the N termini of the molecule (Siegel et al. , 1999; Colquhoun and Sivilotti, 2004; “Nicotinic acetylch oline receptors”, 2006). “The electrostatic isopotential surface--a surface representing constant electric potential--for a model of the nicotinic acetylcholine receptor. The model was developed by Igor Tsigelny, Naoya Sugiyama, and Palmer Taylor at the Departments of Pharmacology and Chemistry/Biochemistry at the University of California, San Diego, in collaboration with Steven M. Sine at the Mayo Foundation in Rochester, Minnesota. Visualized by Igor Tsigelny at SDSC” (San Diego Supercomputer Center, n.d. )There are two types of receptors, the neuronal or ganglionic receptors and the neuromuscular receptors. The neuronal receptors are located in the central nervous system that controls the brain and spinal cord of vertebrates  and also on all autonomic ganglia, a collection of neurons in the autonomic nervous system. The neuromuscular type is responsible for muscle contraction which is done when receptors in the neuromuscular junctions of somatic muscles are activated (“ Nicotinic acetylcholine receptors”, n.d. ).