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GABA_A receptors are the principal mediators of rapid inhibitor synaptic transmission in the brain, and a decline in GABA_A signalling leads to diseases including epilepsy, insomnia, anxiety and autism; here, the first X-ray crystal structure of a human GABA_A receptor, the human β3 homopentamer, reveals structural features unique for this receptor class and uncovers the locations of key disease-causing mutations.

Many current immunoassays require multiple washing, incubation and optimization steps. Here the authors present Ratiometric Plug-and-Play Immunodiagnostics (RAPPID), a generic assay platform that uses ratiometric bioluminescent detection to allow sandwich immunoassays to be performed directly in solution.

The diverse makeup and assembly of subunits augment the structure, physiology and pharmacology of GABA_A receptors.

Cryo-electron microscopy structures are reported in which the full-length human α1β3γ2L GABA_A receptor in lipid nanodiscs is bound to the channel-blocker picrotoxin, the competitive antagonist bicuculline, the agonist GABA, and the benzodiazepines alprazolam and diazepam.

Advances in electron cryo-microscopy hardware allow proteins to be studied at atomic resolution.

Analysis of proteins within their native environment can confirm and extend in vitro–derived conclusions. NMR analysis of superoxide dismutase 1 in live human cells now corroborates previously identified steps on the maturation pathway and demonstrates copper-independent function of the chaperone CCS.

Combining expansion microscopy with super-resolution radial fluctuations captures the morphology of single proteins.

Megabodies, built by grafting nanobodies onto larger protein scaffolds, help alleviate problems of particle size and preferential orientation at the water–air interfaces during cryo-EM based structure determination experiments and are shown to be generalizable to soluble and membrane-bound proteins.

A high-resolution cryo-electron microscopy structure is reported for the full-length human α1β3γ2L GABA_A receptor, functionally reconstituted in lipid nanodiscs.

Eph receptors are cell surface protein tyrosine kinases that mediate cell-cell communication. The crystal structure of the full ectodomain of unliganded human EphA2 (eEphA2) reveals that it forms linear arrays of staggered, parallel receptors, whereas that of eEphA2 in complex with ephrinA5 forms a more elaborate assembly with interfaces that are crucial for localization at cell-cell contacts and for activation-dependent degradation.

Receptor protein tyrosine phosphatase sigma (RPTPσ) promotes both neurite outgrowth and synaptic organization. Here, Coles et al.present the structural basis for this switch in function, whereby TrkC on the postsynaptic membrane and heparan sulphate proteoglycans compete for the same binding surface on RPTPσ.

Here, Kasaragod et al. solve structures of the GABA_A receptor α5 subunit in complex with different classes of positive and negative allosteric modulators to explain the binding modes and the molecular basis of selectivity.

Crystal structures and functional assays of a chimeric GABA_A receptor in apo and pregnanolone-bound states reveal how neurosteroid binding alters receptor conformation to modulate channel opening.

Hedgehog (Hh) signaling molecules are involved in multiple developmental processes. Hedgehog-interacting protein (Hhip) binds and inhibits vertebrate Hh proteins. Structures of HHIP in complex with SHH and DHH now show a distinct binding site from previous ligand structures, with metal-binding sites having a role in interaction.

The receptor tyrosine phosphatase CD45 has an important role in T cell activation. Davis and colleagues resolve the structure of CD45 and provide molecular insights into how it contributes to productive T cell receptor triggering.

Gilean McVean and colleagues report the results of a large-scale clinical genome sequencing project spanning a broad spectrum of disorders. They identify factors influencing successful genetic diagnosis and highlight the challenges of interpreting findings for genetically heterogeneous disorders.

WIF-1 inhibits Wnt signaling by binding Wnt ligands. Structural and biochemical analysis of WIF-1 shows the EGF-like domains wrapping back to contact the ligand-binding WD domain, which also binds a phospholipid near the interaction site for Wnt ligands. The tail of EGF-like domains also harbors a proteoglycan binding site, indicating that all domains of WIF-1 contribute to the regulation of Wnt signaling in vivo.

Given the high degree of similarity between Eph receptors, it has remained unclear how the same ligand can produce different signaling outcomes. The crystal structures of apo and ligand-bound EphA4, combined with cellular assays with chimeric ectodomains, now indicate that the specificity of signaling outcome is largely dictated by clustering properties structurally encoded within the ectodomain.

There are currently two types of antiviral drugs – neutralizing antibodies and small molecule inhibitors. Here, the authors report the development of bicyclic peptides that combine the advantages of both and show their antiviral capacity against SARS-CoV-2 in vitro as well as in small animal models.

This protocol describes a suite of lentiviral transfer plasmids that can be used for high-yield, time- and cost-efficient, and constitutive or inducible production of soluble and membrane proteins in mammalian cell lines.

The interplay between cryo-electron microscopy and cryo-electron tomography to define complex macromolecular assemblies and visualize them in situ is explored.