Hemoglobin Balkh, a Novel Mutation in Codon 132 of α2-Globin Gene [α132(H15) (+T) or :C.396dup (p.Val134fs)]: A Case Report and Insight into the Pathophysiology.

We report a novel mutation on α2-globin gene leading to an elongated α-chain. This novel frameshift mutation was detected in a 13-year-old boy from Balkh province, Afghanistan. DNA analysis identified an insertion of thymine (T) at codon 132 [:c.

Structure of the human dopamine transporter in complex with cocaine.

The dopamine transporter (DAT) is crucial for regulating dopamine signalling and is the prime mediator for the rewarding and addictive effects of cocaine. As part of the neurotransmitter sodium symporter family, DAT uses the Na gradient across cell membranes to transport dopamine against its chemical gradient. The transport mechanism involves both intra- and extracellular gates that control substrate access to a central site.

Cryo-EM structure of the dopamine transporter with a novel atypical non-competitive inhibitor bound to the orthosteric site.

The regulation of dopamine (DA) removal from the synaptic cleft is a crucial process in neurotransmission and is facilitated by the sodium- and chloride-coupled dopamine transporter DAT. Psychostimulant drugs, cocaine, and amphetamine, both block the uptake of DA, while amphetamine also triggers the release of DA. As a result, they prolong or even amplify neurotransmitter signaling.

The Na,K-ATPase in complex with beryllium fluoride mimics an ATPase phosphorylated state.

The Na,K-ATPase generates electrochemical gradients of Na and K across the plasma membrane via a functional cycle that includes various phosphoenzyme intermediates. However, the structure and function of these intermediates and how metal fluorides mimick them require further investigation. Here, we describe a 4.

Structural insights into the inhibition of glycine reuptake.

The human glycine transporter 1 (GlyT1) regulates glycine-mediated neuronal excitation and inhibition through the sodium- and chloride-dependent reuptake of glycine. Inhibition of GlyT1 prolongs neurotransmitter signalling, and has long been a key strategy in the development of therapies for a broad range of disorders of the central nervous system, including schizophrenia and cognitive impairments. Here, using a synthetic single-domain antibody (sybody) and serial synchrotron crystallography, we have determined the structure of GlyT1 in complex with a benzoylpiperazine chemotype inhibitor at 3.

Expression strategies for structural studies of eukaryotic membrane proteins.

Integral membrane proteins in eukaryotes are central to various cellular processes and key targets in structural biology, biotechnology and drug development. However, the number of available structures for eukaryotic membrane protein belies their physiological importance. Recently, the number of available eukaryotic membrane protein structures has been steadily increasing due to the development of novel strategies in construct design, expression and structure determination.

A conserved leucine occupies the empty substrate site of LeuT in the Na(+)-free return state.

Bacterial members of the neurotransmitter:sodium symporter (NSS) family perform Na(+)-dependent amino-acid uptake and extrude H(+) in return. Previous NSS structures represent intermediates of Na(+)/substrate binding or intracellular release, but not the inward-to-outward return transition. Here we report crystal structures of Aquifex aeolicus LeuT in an outward-oriented, Na(+)- and substrate-free state likely to be H(+)-occluded.

Sites of Anesthetic Inhibitory Action on a Cationic Ligand-Gated Ion Channel.

Pentameric ligand-gated ion channels have been identified as the principal target of general anesthetics (GA), whose molecular mechanism of action remains poorly understood. Bacterial homologs, such as the Gloeobacter violaceus receptor (GLIC), have been shown to be valid functional models of GA action. The GA bromoform inhibits GLIC at submillimolar concentration.

Structural Studies of Nicotinic Acetylcholine Receptors: Using Acetylcholine-Binding Protein as a Structural Surrogate.

Nicotinic acetylcholine receptors (nAChRs) are members of the pentameric ligand-gated ion channel superfamily that play important roles in the control of neurotransmitter release in the central and peripheral nervous system. These receptors are important therapeutic targets for the development of drugs against a number of mental health disorders and for marketed smoking cessation aids. Unfortunately, drug discovery has been hampered by difficulties in obtaining sufficiently selective compounds.

Acetylcholine-Binding Protein Engineered to Mimic the α4-α4 Binding Pocket in α4β2 Nicotinic Acetylcholine Receptors Reveals Interface Specific Interactions Important for Binding and Activity.

Neuronal α4β2 nicotinic acetylcholine receptors are attractive drug targets for psychiatric and neurodegenerative disorders and smoking cessation aids. Recently, a third agonist binding site between two α4 subunits in the (α4)(3)(β2)(2) receptor subpopulation was discovered. In particular, three residues, H142, Q150, and T152, were demonstrated to be involved in the distinct pharmacology of the α4-α4 versus α4-β2 binding sites.

From shellfish poisoning to neuroscience.

In this issue of Structure, Bourne et al. (2015) report X-ray structures of acetylcholine binding protein with two fast-acting phycotoxins from the pinnatoxin family. The results may pave the way for development of new CNS-penetrant and subtype-selective nAChR antagonists.

Engineered α4β2 nicotinic acetylcholine receptors as models for measuring agonist binding and effect at the orthosteric low-affinity α4-α4 interface.

The nicotinic acetylcholine receptor α4β2 is important for normal mammalian brain function and is known to express in two different stoichiometries, (α4)2(β2)3 and (α4)3(β2)2. While these are similar in many aspects, the (α4)3(β2)2 stoichiometry differs by harboring a third orthosteric acetylcholine binding site located at the α4-α4 interface. Interestingly, the third binding site has, so far, only been documented using electrophysiological assays, actual binding affinities of nicotinic receptor ligands to this site are not known.

Crystallographic studies of pharmacological sites in pentameric ligand-gated ion channels.

Background: Pentameric ligand-gated ion channels (pLGICs) mediate fast chemical transmission of nerve signals in the central and peripheral nervous system. On the functional side, these molecules respond to the binding of a neurotransmitter (glycine, GABA, acetylcholine or 5HT3) in the extracellular domain (ECD) by opening their ionotropic pore in the transmembrane domain (TMD). The response to the neurotransmitter binding can be modulated by several chemical compounds acting at topographically distinct sites, as documented by a large body of literature.

Crystal structures of a pentameric ligand-gated ion channel provide a mechanism for activation.

Pentameric ligand-gated ion channels mediate fast chemical transmission of nerve signals. The structure of a bacterial proton-gated homolog has been established in its open and locally closed conformations at acidic pH. Here we report its crystal structure at neutral pH, thereby providing the X-ray structures of the two end-points of the gating mechanism in the same pentameric ligand-gated ion channel.

Crystal structure of Lymnaea stagnalis AChBP complexed with the potent nAChR antagonist DHβE suggests a unique mode of antagonism.

Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated ion channels that belong to the Cys-loop receptor superfamily. These receptors are allosteric proteins that exist in different conformational states, including resting (closed), activated (open), and desensitized (closed) states. The acetylcholine binding protein (AChBP) is a structural homologue of the extracellular ligand-binding domain of nAChRs.