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28 results on '"Jang, Kiyoung"'

1. Structural evidence for visual arrestin priming via complexation of phosphoinositols

Author

Sander, Christopher L, Luu, Jennings, Kim, Kyumhyuk, Furkert, David, Jang, Kiyoung, Reichenwallner, Joerg, Kang, MinSoung, Lee, Ho-Jun, Eger, Bryan T, Choe, Hui-Woog, Fiedler, Dorothea, Ernst, Oliver P, Kim, Yong Ju, Palczewski, Krzysztof, and Kiser, Philip D

Subjects
Biochemistry and Cell Biology, Biological Sciences, Eye Disease and Disorders of Vision, Animals, Arrestin, Cattle, Crystallography, X-Ray, Inositol Phosphates, Mice, Models, Molecular, Protein Conformation, Protein Domains, Rhodopsin, Sequence Analysis, RNA, Single-Cell Analysis, (1, 4, 5) myo-D-inositol triphosphate, G protein-coupled receptor, GPCR, InsP(3), InsP(6), arrestin, crystal structure, myo-D-inositol hexakisphosphate, phospholipase C, photoreceptor, phototransduction, retina, vision, Chemical Sciences, Information and Computing Sciences, Biophysics, Biological sciences, Chemical sciences
Abstract

Visual arrestin (Arr1) terminates rhodopsin signaling by blocking its interaction with transducin. To do this, Arr1 translocates from the inner to the outer segment of photoreceptors upon light stimulation. Mounting evidence indicates that inositol phosphates (InsPs) affect Arr1 activity, but the Arr1-InsP molecular interaction remains poorly defined. We report the structure of bovine Arr1 in a ligand-free state featuring a near-complete model of the previously unresolved C-tail, which plays a crucial role in regulating Arr1 activity. InsPs bind to the N-domain basic patch thus displacing the C-tail, suggesting that they prime Arr1 for interaction with rhodopsin and help direct Arr1 translocation. These structures exhibit intact polar cores, suggesting that C-tail removal by InsP binding is insufficient to activate Arr1. These results show how Arr1 activity can be controlled by endogenous InsPs in molecular detail.

Published
2022

3. OPERA: Reasoning about continuous common knowledge in asynchronous distributed systems

Author

Choi, Sang-Min, Park, Jiho, Nguyen, Quan, Cronje, Andre, Jang, Kiyoung, Cheon, Hyunjoon, Han, Yo-Sub, and Ahn, Byung-Ik

Subjects
Computer Science - Distributed, Parallel, and Cluster Computing
Abstract

This paper introduces a new family of consensus protocols, namely \emph{Lachesis-class} denoted by $\mathcal{L}$, for distributed networks with guaranteed Byzantine fault tolerance. Each Lachesis protocol $L$ in $\mathcal{L}$ has complete asynchrony, is leaderless, has no round robin, no proof-of-work, and has eventual consensus. The core concept of our technology is the \emph{OPERA chain}, generated by the Lachesis protocol. In the most general form, each node in Lachesis has a set of $k$ neighbours of most preference. When receiving transactions a node creates and shares an event block with all neighbours. Each event block is signed by the hashes of the creating node and its $k$ peers. The OPERA chain of the event blocks is a Directed Acyclic Graph (DAG); it guarantees practical Byzantine fault tolerance (pBFT). Our framework is then presented using Lamport timestamps and concurrent common knowledge. Further, we present an example of Lachesis consensus protocol $L_0$ of our framework. Our $L_0$ protocol can reach consensus upon 2/3 of all participants' agreement to an event block without any additional communication overhead. $L_0$ protocol relies on a cost function to identify $k$ peers and to generate the DAG-based OPERA chain. By creating a binary flag table that stores connection information and share information between blocks, Lachesis achieves consensus in fewer steps than pBFT protocol for consensus.

Published
2018

7. Strategy to Select an Appropriate Cryoprotectant for an X-ray Study of Escherichia coliGAPDH Crystals

Author

Hlaing, Sandi Hnit San, Jang, Kiyoung, Kim, Hyun Gi, Kim, Nahyun, Lee, Kui-Jae, Choe, Hui-Woog, Park, Jung Hee, and Kim, Yong Ju

Abstract

The treatment of protein crystals with an appropriate cryoprotectant and immediate freezing in liquid nitrogen before data collection at the synchrotron source is one of the critical steps for determining the structure of three-dimensional biomacromolecule (protein) crystals. Three-dimensional crystal structures of glyceraldehyde 3-phosphate dehydrogenase (GAPDH: EC 1.2.1.12) have been determined in many species, including Escherichia coli(Ec), using crystallization and cryoprotectant agents. Herein, we describe the cryogenic effects on E. coliGAPDH (EcGAPDH) crystals that were crystallized with 2.8 M ammonium sulfate as a precipitating agent. Fully grown EcGAPDH crystals were frozen under various cryoprotection treatments, including 11 different cryoprotectants with different protein mechanisms. We found that the lattices of some EcGAPDH crystals stabilized well with 3.5 M ammonium sulfate, which is not typically used as a cryoprotectant because it does not have antifreeze properties. The observed stabilization may be due to an osmotic effect induced by the difference in concentration between the cryoprotectant (3.5 M) and the precipitating agent (2.8 M), which may lead to dehydration of the inside of the EcGAPDH crystals. These findings suggest that the use of ammonium sulfate at a certain concentration (3.5 M), higher than the precipitating agent, may be a useful cryoprotectant for other protein crystals. Additionally, although the addition of salts with antifreezing properties such as lithium sulfate (1 M) or sodium formate (3 M) to the crystallization condition of EcGAPDH (2.8 M ammonium sulfate) successfully provided cryoprotection, it did not yield improved X-ray data compared to crystals of EcGAPDH cryoprotected with 3.5 M ammonium sulfate or trehalose.

Published
2023
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28. Novel Cultivation of six-year-old Korean Ginseng (Panax ginseng) in pot: From Non-Agrochemical Management to Increased Ginsenoside

Author

Hwang, Kyung Ho, Kim, Hyun Gi, Jang, Kiyoung, and Kim, Yong Ju

Abstract

Ginseng (Panax ginsengMeyer) is a perennial plant belonging to the Araliaceae family that is known to have various beneficial effects including improving memory loss and spatial cognitive ability, and anti-cancer and anti-diabetes activity. Its functional benefits also include improving liver function, regulating blood pressure, stress, and providing antioxidant activity. Usually, various agrochemicals are used in cultivating ginseng preventing from many diseases.

Published
2023
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