We have recently discovered an allosteric switch in Ras, bringing an additional level of complexity to this GTPase whose mutants are involved in nearly 30% of cancers. Upon activation of the allosteric switch, there is a shift in helix 3/loop 7 associated with a disorder to order transition in the active site. Here, we use a combination of multiple solvent crystal structures and computational solvent mapping (FTMap) to determine binding site hot spots in the “off” and “on” allosteric states of the GTP-bound form of H-Ras. Thirteen sites are revealed, expanding possible target sites for ligand binding well beyond the active site. Comparison of FTMaps for the H and K isoforms reveals essentially identical hot spots. Furthermore, using NMR measurements of spin relaxation, we determined that K-Ras exhibits global conformational dynamics very similar to those we previously reported for H-Ras. We thus hypothesize that the global conformational rearrangement serves as a mechanism for allosteric coupling between the effector interface and remote hot spots in all Ras isoforms. At least with respect to the binding sites involving the G domain, H-Ras is an excellent model for K-Ras and probably N-Ras as well. Ras has so far been elusive as a target for drug design. The present work identifies various unexplored hot spots throughout the entire surface of Ras, extending the focus from the disordered active site to well-ordered locations that should be easier to target.

We present “in-membrane chemical modification” (IMCM) for obtaining selective chromophore labeling of intracellular surface cysteines in G protein-coupled receptors (GPCRs) with minimal mutagenesis. Practical use of IMCM is illustrated with site-specific introduction of chromophores for NMR and fluorescence spectroscopy in the human κ-opioid receptor (KOR) and the human A2A adenosine receptor (A2AAR). IMCM is applicable for a wide range of in-vitro studies of GPCRs, including single molecule spectroscopy, and is a promising platform for in-cell spectroscopy experiments.

Background: The economic effects of the COVID-19 crisis are not like anything the U.S. health care system has ever experienced. Methods: As we begin to emerge from the peak of the COVID-19 pandemic, we need to plan the sustainable resumption of elective procedures. We must first ensure the safety of our patients and surgical staff. It must be a priority to monitor the availability of supplies for the continued care of patients suffering from COVID-19. As we resume elective orthopedic surgery and total joint arthroplasty, we must begin to reduce expenses by renegotiating vendor contracts, use ambulatory surgery centers and hospital outpatient departments in a safe and effective manner, adhere to strict evidence-based and COVID-19eadjusted practices, and incorporate telemedicine and other technology platforms when feasible for health care systems and orthopedic groups to survive economically. Results: The return to normalcy will be slow and may be different than what we are accustomed to, but we must work together to plan a transition to a more sustainable health care reality which accommodates a COVID-19 world. Conclusion: Our goal should be using these lessons to achieve a healthy and successful 2021 fiscal year.

The structure of the dynorphin (1-13) peptide (dynorphin) bound to the human kappa opioid receptor (KOR) has been determined by liquid-state NMR spectroscopy.