The delta opioid receptor (DOR), a physiologically relevant prototype for G protein–coupled receptors, is retained in intracellular compartments in neuronal cells. This retention is mediated by a nerve growth factor (NGF)-regulated checkpoint that delays the export of DOR from the trans-Golgi network. How DOR is selectively retained in the Golgi, in the midst of dynamic membrane transport and cargo export, is a fundamental unanswered question. Here we address this by investigating sequence elements on DOR that regulate DOR surface delivery, focusing on the C-terminal tail of DOR that is sufficient for NGF-mediated regulation. By systematic mutational analysis, we define conserved dual bi-arginine (RXR) motifs that are required for NGF- and phosphoinositide-regulated DOR export from intracellular compartments in neuroendocrine cells. These motifs were required to bind the coatomer protein I (COPI) complex, a vesicle coat complex that mediates primarily retrograde cargo traffic in the Golgi. Our results suggest that interactions of DOR with COPI, via atypical COPI motifs on the C-terminal tail, retain DOR in the Golgi. These interactions could provide a point of regulation of DOR export and delivery by extracellular signaling pathways.
Kinetochores are the chromosomal attachment points for spindle microtubules. They are also signaling hubs that control major cell cycle transitions and coordinate chromosome folding. Most well-studied eukaryotes rely on a conserved set of factors, which are divided among two loosely-defined groups, for these functions. Outer kinetochore proteins contact microtubules or regulate this contact directly. Inner kinetochore proteins designate the kinetochore assembly site by recognizing a specialized nucleosome containing the H3 variant Cse4/CENP-A. We previously determined the structure, resolved by cryo-electron microscopy (cryo-EM), of the yeast Ctf19 complex (Ctf19c, homologous to the vertebrate CCAN), providing a high-resolution view of inner kinetochore architecture (Hinshaw and Harrison, 2019). We now extend these observations by reporting a near-atomic model of the Ctf3 complex, the outermost Ctf19c sub-assembly seen in our original cryo-EM density. The model is sufficiently well-determined by the new data to enable molecular interpretation of Ctf3 recruitment and function.
Water scarcity affects 1.2 billion people on a global scale, representing nearly one fifth of the human population. In some regions, current water sources are being depleted faster than they are renewed and the majority of this depletion is being used for irrigation and agricultural purposes. At any given time, the atmosphere contains 3400 trillion gallons of water vapor, which would be enough to cover the entire Earth in 1 inch of water. Herein, we describe the design of an innovative solution to water scarcity in regions with medium to high humidity -Atmospheric Water Generators (AWG). This device converts water vapor into liquid water and is designed for agricultural and irrigation purposes in regions where water scarcity exists. More specifically, two AWG concepts were developed by our team, one utilizing Peltier devices and the other a heat exchanger, in order to allow multiple design alternatives to be considered. The Peltier-based concept works by applying current to induce a temperature gradient in order to cool and condense the surrounding air. The heat exchanger concept works by cycling a coolant that is cooled by a lower ground temperature. Both AWG concepts were designed utilizing sustainable engineering principles to minimize energy consumption and cost (particularly when compared to AWGs currently on the market). The designs are estimated to create enough water daily to grow 2 fruit trees (1 gallon a week) at an example test condition of 60% relative humidity and 85°F.
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