Nicotinic acetylcholine receptors, or nAChRs, are receptor polypeptides that respond to the neurotransmitter acetylcholine. Nicotinic receptors also respond to drugs such as the agonist nicotine. They are found in the central and peripheral nervous system, muscle, and many other tissues of many organisms. At the neuromuscular junction they are the primary receptor in muscle for motor nerve-muscle communication that controls muscle contraction. In the peripheral nervous system: (1) they transmit outgoing signals from the presynaptic to the postsynaptic cells within the sympathetic and parasympathetic nervous system, and (2) they are the receptors found on skeletal muscle that receive acetylcholine released to signal for muscular contraction. In the immune system, nAChRs regulate inflammatory processes and signal through distinct intracellular pathways. In insects, the cholinergic system is limited to the central nervous system.
Chromosome 8 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 8 spans about 146 million base pairs and represents between 4.5 and 5.0% of the total DNA in cells.
The Urokinase receptor, also known as urokinase plasminogen activator surface receptor (uPAR) or CD87, is a protein encoded in humans by the PLAUR gene. It is a multidomain glycoprotein tethered to the cell membrane with a glycosylphosphotidylinositol (GPI) anchor. uPAR was originally identified as a saturable binding site for urokinase on the cell surface.
α-Bungarotoxin is one of the bungarotoxins, components of the venom of the elapid Taiwanese banded krait snake. It is a type of α-neurotoxin, a neurotoxic protein that is known to bind competitively and in a relatively irreversible manner to the nicotinic acetylcholine receptor found at the neuromuscular junction, causing paralysis, respiratory failure, and death in the victim. It has also been shown to play an antagonistic role in the binding of the α7 nicotinic acetylcholine receptor in the brain, and as such has numerous applications in neuroscience research.
The human muscarinic acetylcholine receptor M5, encoded by the CHRM5 gene, is a member of the G protein-coupled receptor superfamily of integral membrane proteins. It is coupled to Gq protein. Binding of the endogenous ligand acetylcholine to the M5 receptor triggers a number of cellular responses such as adenylate cyclase inhibition, phosphoinositide degradation, and potassium channel modulation. Muscarinic receptors mediate many of the effects of acetylcholine in the central and peripheral nervous system. The clinical implications of this receptor have not been fully explored; however, stimulation of this receptor is known to effectively decrease cyclic AMP levels and downregulate the activity of protein kinase A (PKA).
α-Cobratoxin is a substance of the venom of certain Naja cobras. It is a nicotinic acetylcholine receptor (nAChR) antagonist which causes paralysis by preventing the binding of acetylcholine to the nAChR.
Neuronal acetylcholine receptor subunit beta-2 is a protein that in humans is encoded by the CHRNB2 gene.
Neuronal acetylcholine receptor subunit alpha-3, also known as nAChRα3, is a protein that in humans is encoded by the CHRNA3 gene. The protein encoded by this gene is a subunit of certain nicotinic acetylcholine receptors (nAchR). Research with mecamylamine in animals has implicated alpha-3-containing nAChRs in the abusive and addictive properties of ethanol.
The alpha-7 nicotinic receptor, also known as the α7 receptor, is a type of nicotinic acetylcholine receptor implicated in long-term memory, consisting entirely of α7 subunits. As with other nicotinic acetylcholine receptors, functional α7 receptors are pentameric [i.e., (α7)5 stoichiometry].
Secreted Ly-6/uPAR-related protein 1 is a protein that in humans is encoded by the SLURP1 gene. It exerts anti-inflammatory effects, acts as a tumor suppressor, and antagonizes nicotinic receptors.
Neuronal acetylcholine receptor subunit alpha-2, also known as nAChRα2, is a protein that in humans is encoded by the CHRNA2 gene. The protein encoded by this gene is a subunit of certain nicotinic acetylcholine receptors (nAchR).
Melanoma-associated antigen 11 is a protein that in humans is encoded by the MAGEA11 gene. It is also involved in the androgen and progesterone receptor signaling pathways.
Ly6/PLAUR domain-containing protein 1 is a protein that in humans is encoded by the LYPD1 gene.
RIC-3 also known as resistance to inhibitors of cholinesterase 3 is a chaperone protein that in humans is encoded by the RIC3 gene. The RIC3 gene was first discovered in C. elegans. RIC-3 protein is conserved in most animals and influences the maturation of various ligand gated ion channels including the serotonin 5-HT3 receptor and nicotinic acetylcholine receptors, particularly the homomeric α7 nicotinic receptor. RIC-3 enhances currents generated by these receptors by expediting receptor transport to the cell surface and by increasing receptor number.
Cholinergic receptor, nicotinic, alpha 6, also known as nAChRα6, is a protein that in humans is encoded by the CHRNA6 gene. The CHRNA6 gene codes for the α6 nicotinic receptor subunit that is found in certain types of nicotinic acetylcholine receptors found primarily in the brain. Neural nicotinic acetylcholine receptors containing α6 subunits are expressed on dopamine-releasing neurons in the midbrain, and dopamine release following activation of these neurons is thought to be involved in the addictive properties of nicotine. Due to their selective localisation on dopaminergic neurons, α6-containing nACh receptors have also been suggested as a possible therapeutic target for the treatment of Parkinson's disease. In addition to nicotine, research in animals has implicated alpha-6-containing nAChRs in the abusive and addictive properties of ethanol, with mecamylamine demonstrating a potent ability to block these properties.
The LU domain is an evolutionarily conserved protein domain of the three-finger protein superfamily. This domain is found in the extracellular domains of cell-surface receptors and in either GPI-anchored or secreted globular proteins, for example the Ly-6 family, CD59, and Sgp-2.
α-Neurotoxins are a group of neurotoxic peptides found in the venom of snakes in the families Elapidae and Hydrophiidae. They can cause paralysis, respiratory failure, and death. Members of the three-finger toxin protein family, they are antagonists of post-synaptic nicotinic acetylcholine receptors (nAChRs) in the neuromuscular synapse that bind competitively and irreversibly, preventing synaptic acetylcholine (ACh) from opening the ion channel. Over 100 α-neurotoxins have been identified and sequenced.
Ly6/neurotoxin 1 is a protein in humans that is encoded by the LYNX1 gene. Alternatively spliced variants encoding different isoforms have been identified.
Ly6 also known as lymphocyte antigen 6 or urokinase-type plasminogen activator receptor (uPAR) is family of proteins that share a common structure but differ in their tissue expression patterns and function. Ly6 are cysteine-rich proteins that form disulfide bridges and contain a LU domain. These proteins are GPI-anchored to the cell membrane or are secreted. A total of 35 human and 61 mouse Ly6 family members have been identified. Depending on which tissues they are expressed in, LY6 family members have different roles. They are expressed in various types of tissues and their expression dependent on the stage of cell differentiation. For example, they are involved in cell proliferation, cell migration, cell–cell interactions, immune cell maturation, macrophage activation, and cytokine production. Their overexpression or dysregulation, for example due to point mutations, is associated with tumorogenesis and autoimmune diseases. This family was discovered in the 1970s, and these proteins are still used as markers of distinct stage of leukocyte differentiation.
Three-finger proteins or three-finger protein domains are a protein superfamily consisting of small, roughly 60-80 amino acid residue protein domains with a common tertiary structure: three beta strand loops extended from a hydrophobic core stabilized by disulfide bonds. The family is named for the outstretched "fingers" of the three loops. Members of the family have no enzymatic activity, but are capable of forming protein-protein interactions with high specificity and affinity. The founding members of the family, also the best characterized by structure, are the three-finger toxins found in snake venom, which have a variety of pharmacological effects, most typically by disruption of cholinergic signaling. The family is also represented in non-toxic proteins, which have a wide taxonomic distribution; 3FP domains occur in the extracellular domains of some cell-surface receptors as well as in GPI-anchored and secreted globular proteins, usually involved in signaling.
