Biochemistry Commons^™

In Situ Microwave Fixation Provides An Instantaneous Snapshot Of The Brain Metabolome, Jelena A. Juras, Madison B. Webb, Lyndsay E. A. Young, Kia H. Markussen, Tara R. Hawkinson, Michael D. Buoncristiani, Kayli E. Bolton, Peyton T. Coburn, Meredith I. Williams, Lisa P. Y. Sun, William C. Sanders, Ronald C. Bruntz, Lindsey R. Conroy, Chi Wang, Matthew S. Gentry, Bret N. Smith, Ramon C. Sun

Markey Cancer Center Faculty Publications

Brain glucose metabolism is highly heterogeneous among brain regions and continues postmortem. In particular, we demonstrate exhaustion of glycogen and glucose and an increase in lactate production during conventional rapid brain resection and preservation by liquid nitrogen. In contrast, we show that these post- mortem changes are not observed with simultaneous animal sacrifice and in situ fixation with focused, high- power microwave. We further employ microwave fixation to define brain glucose metabolism in the mouse model of streptozotocin-induced type 1 diabetes. Using both total pool and isotope tracing analyses, we identified global glucose hypometabolism in multiple brain regions, evidenced by …

Targeting Lncrna Ddit4-As1 Sensitizes Triple Negative Breast Cancer To Chemotherapy Via Suppressing Of Autophagy, Ting Jiang, Jiaojiao Zhu, Shilong Jiang, Zonglin Chen, Ping Xu, Rong Gong, Changxin Zhong, Yueying Cheng, Xinyuan Sun, Wenjun Yi, Jinming Yang, Wenhu Zhou, Yan Cheng

Markey Cancer Center Faculty Publications

In this study, it is found that the lncRNA, DNA damage inducible transcript 4 antisense RNA1 (DDIT4-AS1), is highly expressed in triple-negative breast cancer (TNBC) cell lines and tissues due to H3K27 acetylation in the promoter region, and promotes the proliferation, migration, and invasion of TNBC cells via activating autophagy. Mechanistically, it is shown that DDIT4-AS1 induces autophagy by stabilizing DDIT4 mRNA via recruiting the RNA binding protein AUF1 and promoting the interaction between DDIT4 mRNA and AUF1, thereby inhibiting mTOR signaling pathway. Furthermore, silencing of DDIT4-AS1 enhances the sensitivity of TNBC cells to chemotherapeutic agents such as paclitaxel both …

Simulating A Flexible Water Model As Rigid: Best Practices And Lessons Learned, Raymond Weldon, Feng Wang

Chemistry & Biochemistry Faculty Publications and Presentations

Two ways to create rigid versions of flexible models are explored. The rigid model can assume the Model’s Geometry (MG) as if the molecule is not interacting with any other molecules or the ensemble averaged geometry (EG) under a particular thermodynamic condition. Although the MG model is more straightforward to create, it leads to relatively poor performance. The EG model behaves similarly to the corresponding flexible model (the FL model) and, in some cases, agrees even better with experiments. While the difference between the EG and the FL models is mostly a result of flexibility, the MG and EG models …

Toward The Yeast Surface Display Of Microviridin B, Jillian Leigh Stafford

Chemistry and Chemical Biology ETDs

Humans have turned to natural products for medicinal therapeutics for millennia. In recent years, the ribosomally synthesized and post-translationally modified peptide (RiPP) class of natural products have garnered a lot of attention due to their ability for heterologous expression, relative ease of mutation, and vast biological activates. Microviridins are a family of RiPPs that contain a tricyclic cage-like structure through the formation of two lactone rings and one lactam ring catalyzed by two ATP-grasp ligase family enzymes. Microviridins are potent inhibitors of serine proteases and mutational studies of a small number of residues indicates the potential of peptide engineering protease …

Mutating Tetur02g09850 Originated From Spider Mites To Enhance Crystallization, Hayley Cash

Senior Theses

This study aimed to explain and adequately utilize several common biochemical laboratory techniques to mutate a portion of the nucleic acid sequence within a specific protein. This protein, referred to as Tetur02g09850 is originated from Tetranychus Urticae, or the Two-Spotted Spider Mite. This mite causes excessive damage to crops and is known to be extremely resistant to most common pesticides. For this reason, understanding the protein structure could be used to explain this acaricide resistance and aid in the development of more effective pesticides. Some of the testing utilized was site-directed mutagenesis, IMAC and gel filtration for protein purification, gel …

The Function Of Transport Protein Mfl1 In Arabidopsis Thaliana, Joseph Qian

LSU Master's Theses

Photosynthesis serves as the primary process for plants to synthesize ATP and sugar molecules, however, this reaction requires many cofactors such as heme, plastoquinone, and iron-sulfur clusters to assist in energy gathering and electron transfer steps. Many of these require trace metals, such as iron, to cross across the chloroplast membranes and be incorporated into proteins and other organic molecules to form useable cofactors. The light-independent reactions of photosynthesis are also inefficient, with up to 25% of the photosynthetic energy wasted to metabolize the toxic waste product glycolate. The cellular logistics of both photorespiration and iron transport have been studied, …

Polyphenolic Content And Radical Scavenging Activities Of The Peel, Pulp And Seed Of Avocado (Persea Americana Mill.) Grown In Tanzania, Ibrahim Juma, Jan-Eric Englund, Rodomiro Ortiz, Mulatu Geleta, Donatha D. Tibuhwa, Anders S. Carlsson, Agnes Nyomora, Moneim Fatih, Helena Persson Hovmalm

Tanzania Journal of Science

Avocado is a healthy fruit and the consumption is continuously growing worldwide. The fruit contains polyphenolic compounds with antioxidant effects. Globally, research has been devoted to exploring the fruit quality, especially compounds with antioxidant effects, from different avocado-growing sites. However, the fruit quality of the Tanzanian avocado has so far not been investigated. In this study, the contents of polyphenols in peel, pulp and seed of avocados sampled in south-western Tanzania are described. The levels of total polyphenolic and flavonoid contents were measured, and antioxidant activity was evaluated using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The total polyphenolic content was highest in …

Traffic Lights For Catalysis: Stimuli-Responsive Molecular And Extended Catalytic Systems, Grace C. Thaggard, Johanna Haimeri, Roland A. Fischer Prof. Dr., Kyoung Chul Park, Natalia B. Shustova Prof. Dr.

Faculty Publications

The advances made in the field of stimuli-responsive catalysis during the last five years with a focus on the novel recently-emerged directions and applications have been surveyed. Metal-free catalysts and organometallic complexes, as well as biomimetic systems and extended structures, which display switchable catalytic activity for a variety of organic transformations, are discussed. Light-activated systems comprised of photochromic molecules capable of modulating reaction rate, yield, or enantioselectivity based on geometric and electronic changes associated with photoisomerization are the focus of the detailed discussion. Alternative stimuli, including pH and temperature, which could be applied either alone or in combination with light, …

Evaluation Of Free Radical Scavenging  Activity Of Sauce And Formulation Of Tamarindus Indica (L.) And Prunus Domestica (L.) Fruits, Zulnoreen Sarfaraz, Mehmooda Munazir, Mubashrah Munir, Asma Ahmed, Rehana Badar, Ayesha Tahir

Journal of Bioresource Management

The formulation and sauce of Tamarindus indica  (L.) and Prusnus  dometica (L.) are very popular recipes across globe. But, not even a single study existed on free-radical scavenging activity (FRSA) of afore-mentioned recipes. So, the present study was designed to bridge this gap of information. The FRSA of individual samples were also determined and compared with that of combinations of both. The highest value for FRSA among all samples was that of T. indica (158.9732 ± 12.658 % at 100 μg ml^-1). It was followed by that of individual extract of P. domestica fruit (96.647 ± 0.554 %). …

Stabilizing G-Quadruplex Dna And Rna Structures With Ionic Liquids, Timothy Vaden

College of Science & Mathematics Departmental Research

Stabilizing DNA and RNA for long-term room-temperature storage is important for many biotechnological applications including oncology pharmaceuticals and mRNA-based vaccines (e.g. Covid vaccines). This poster shows that ionic liquids can improve the thermal stability of G-quadruplex DNA and RNA structures, and motivates further studies of ionic liquid-based materials for DNA / RNA stabilization.

Purification And Kinetic Characterization Of Mutant R111v Human Cytosolic Malate Dehydrogenase, Jackson Demartino

Chemistry & Biochemistry Student Scholarship

Metabolic profiling for a variety of cancerous cells indicate significant increases in the levels of glucose consumption. To support uncontrolled cell division, cancer cells also present an uncoupling of glycolysis from the citric acid cycle to promote glucose carbons to the synthesis of biomass, therefore, requiring a constant supply of NAD⁺. Recent studies indicate that cancer cells exhibit upregulated cytosolic malate dehydrogenase (MDH1) activity, which catalyzes the conversion of oxaloacetate to malate with the oxidation of NADH, generating NAD⁺. Given its increased activity, MDH1 may serve as a valuable target for treating cancer. Here we report …

Apkcs Role In Neuroblastoma Cell Signaling Cascades And Implications Of Apkcs Inhibitors As Potential Therapeutics, Sloan Breedy

USF Tampa Graduate Theses and Dissertations

Neuroblastoma (NB) is a cancer that develops in the neuroblasts. It is the most common cancer in children under the age of 1 year, accounting for approximately 6% of all cancers. The prognosis of NB is linked to both age and degree of cell differentiation. This results in a range of survival rates for patients, with outcomes ranging from recurrence and mortality to high survival rates and tumor regression. Our previous work indicated that PKC-ι promotes cell proliferation in NB cells through the PKC-ι/Cdk7/Cdk2 cascade. We report on two atypical protein kinase inhibitors as potential therapeutic candidates against BE(2)-C and …

A Multiscale Mechanistic Model Of Human Dendritic Cells For In-Silico Investigation Of Immune Responses And Novel Therapeutics Discovery, Sara Sadat Aghamiri, Bhanwar Lal Puniya, Rada Amin, Tomáš Helikar

Department of Biochemistry: Faculty Publications

Dendritic cells (DCs) are professional antigen-presenting cells (APCs) with the unique ability to mediate inflammatory responses of the immune system. Given the critical role of DCs in shaping immunity, they present an attractive avenue as a therapeutic target to program the immune system and reverse immune disease disorders. To ensure appropriate immune response, DCs utilize intricate and complex molecular and cellular interactions that converge into a seamless phenotype. Computational models open novel frontiers in research by integrating large-scale interaction to interrogate the influence of complex biological behavior across scales. The ability to model large biological networks will likely pave the …

In Silico Binding Of 2-Aminocyclobutanones To Sars-Cov-2 Nsp13 Helicase And Demonstration Of Antiviral Activity, Thahani S. Habeeb Mohammad, Yash Gupta, Cory T. Reidl, Vlad Nicolaescu, Haley Gula, Ravi Durvasula, Prakasha Kempaiah, Daniel P. Becker Ph.D.

Chemistry: Faculty Publications and Other Works

The landscape of viral strains and lineages of SARS-CoV-2 keeps changing and is currently dominated by Delta and Omicron variants. Members of the latest Omicron variants, including BA.1, are showing a high level of immune evasion, and Omicron has become a prominent variant circulating globally. In our search for versatile medicinal chemistry scaffolds, we prepared a library of substituted α-aminocyclobutanones from an α-aminocyclobutanone synthon (11). We performed an in silico screen of this actual chemical library as well as other virtual 2-aminocyclobutanone analogs against seven SARS-CoV-2 nonstructural proteins to identify potential drug leads against SARS-CoV-2, and more broadly against coronavirus …

Small Gtpase Regulated Intracellular Protein Trafficking In Endothelium, Caitlin Francis

Electronic Theses and Dissertations

Intracellular protein trafficking is the movement of membrane-bound organelles to and from requisite locations within the cell. Small GTPases are a critical component to the spatiotemporal accuracy of intracellular trafficking pathways as they determine the specificity and direction of organelle transport. There exists over 150 small GTPases categorized into 5 sub-families and are employed across all cell types. Despite their universal expression and relevance to cellular function, small GTPases remain incompletely understood across tissue types. In various instances, the trafficking pathway of a particular Rab in one cell type may belong to a completely disparate pathway in another cell type. …

A Single-Cell Gene Expression Atlas Of Human Follicular Aspirates: Identification Of Leukocyte Subpopulations And Their Paracrine Factors, Yohan Choi, Hayce Jeon, Mats Brännström, James W. Akin, Thomas E. Curry, Misung Jo

UK CARES Faculty Publications

Leukocytes are in situ regulators critical for ovarian function. However, little is known about leukocyte subpopulations and their interaction with follicular cells in ovulatory follicles, especially in humans. Single-cell RNA sequencing (scRNA- seq) was performed using follicular aspirates obtained from four IVF patients and identified 13 cell groups: one granulosa cell group, one thecal cell group, 10 subsets of leukocytes, and one group of RBC/platelet. RNA velocity analyses on five granulosa cell populations predicted developmental dynamics denoting two projections of differentiation states. The cell type-specific transcriptomic profiling analyses revealed the presence of a diverse array of leukocyte-derived factors that can …

Loss Of Peroxiredoxin Iv Protects Mice From Azoxymethane/Dextran Sulfate Sodium-Induced Colorectal Cancer Development, Pratik Thapa, Hong Jiang, Na Ding, Yanning Hao, Aziza Alshahrani, Eun Young Lee, Junichi Fujii, Qiou Wei

Markey Cancer Center Faculty Publications

Peroxiredoxin IV (Prx4), a typical two-cysteine-containing member of the peroxidase family, functions as an antioxidant to maintain cellular redox homeostasis through the reduction of reactive oxygen species (ROS) via cycles of oxidation–reduction reactions. Under oxidative stress, all Prxs including Prx4 are inactivated as their catalytic cysteines undergo hyperoxidation, and hyperoxidized two-cysteine Prxs can be exclusively repaired and revitalized through the reduction cycle catalyzed by sulfiredoxin (Srx). Previously, we showed that Prx4 is a preferred substrate of Srx, and knockout of Srx in mice leads to resistance to azoxymethane/dextran sulfate sodium (AOM/DSS)-induced colon carcinogenesis. To further understand the significance of the …

Abstract 1858: Active And Allosteric Site Evolution Directs Ordered Water Use In Kinesin Catalysis, Micquel Downs, David Worthylake, Jessica Richard, Courtney Parke, Elizabeth Kim, Edward J. Wojcik, Sunyoung Kim

School of Graduate Studies Faculty Publications

2023 American Society for Biochemistry and Molecular Biology (ASBMB) Annual Meeting; March 25 - 28, 2023; Seattle, WA

Latexin Regulates Sex Dimorphism In Hematopoiesis Via Gender-Specific Differential Expression Of Microrna 98-3p And Thrombospondin 1, Xiaojing Cui, Cuiping Zhang, Fang Wang, Xinghui Zhao, Shuxia Wang, Jinpeng Liu, Daheng He, Chi Wang, Feng-Chun Yang, Sheng Tong, Ying Liang

Markey Cancer Center Faculty Publications

Hematopoietic stem cells (HSCs) have the ability to self-renew and differentiate to all blood cell types. HSCs and their differentiated progeny show sex/gender differences. The fundamental mechanisms remain largely unexplored. We previously reported that latexin (Lxn) deletion increased HSC survival and repopulation capacity in female mice. Here, we find no differences in HSC function and hematopoiesis in Lxn knockout (Lxn-/- male mice under physiologic and myelosuppressive conditions. We further find that Thbs1, a downstream target gene of Lxn in female HSCs, is repressed in male HSCs. Male-specific high expression of micro- RNA 98-3p (miR98-3p) contributes to Thbs1 suppression in male …

Ferric Chloride-Induced Arterial Thrombosis And Sample Collection For 3d Electron Microscopy Analysis, Smita Joshi, Alexis N. Smith, Kanakanagavalli Shravani Prakhya, Hammodah Rawhi Hammodah Alfar, Joshua Lykins, Ming Zhang, Irina D. Pokrovskaya, Maria A. Aronova, Richard D. Leapman, Brian Storrie, Sidney W. Whiteheart

Saha Cardiovascular Research Center Faculty Publications

Cardiovascular diseases are a leading cause of mortality and morbidity worldwide. Aberrant thrombosis is a common feature of systemic conditions like diabetes and obesity, and chronic inflammatory diseases like atherosclerosis, cancer, and autoimmune diseases. Upon vascular injury, usually the coagulation system, platelets, and endothelium act in an orchestrated manner to prevent bleeding by forming a clot at the site of the injury. Abnormalities in this process lead to either excessive bleeding or uncontrolled thrombosis/insufficient antithrombotic activity, which translates into vessel occlusion and its sequelae. The FeCl3-induced carotid injury model is a valuable tool in probing how thrombosis initiates and progresses …

An Improved Germline Genome Assembly For The Sea Lamprey Petromyzon Marinus Illuminates The Evolution Of Germline-Specific Chromosomes, Nataliya Timoshevskaya, Kaan İ. Eşkut, Vladimir A. Timoshevskiy, Sofia M.C. Robb, Carson Holt, Jon E. Hess, Hugo J. Parker, Cindy F. Baker, Allison K. Miller, Cody Saraceno, Mark Yandell, Robb Krumlauf, Shawn R. Narum, Ralph T. Lampman, Neil J. Gemmell, Jacquelyn Mountcastle, Bettina Haase, Jennifer R. Balacco, Giulio Formenti, Sarah Pelan, Ying Sims, Kerstin Howe, Olivier Fedrigo, Erich D. Jarvis, Jeramiah James Smith

Markey Cancer Center Faculty Publications

Programmed DNA loss is a gene silencing mechanism that is employed by several vertebrate and nonvertebrate lineages, including all living jawless vertebrates and songbirds. Reconstructing the evolution of somatically eliminated (germline-specific) sequences in these species has proven challenging due to a high content of repeats and gene duplications in eliminated sequences and a corresponding lack of highly accurate and contiguous assemblies for these regions. Here, we present an improved assembly of the sea lamprey (Petromyzon marinus) genome that was generated using recently standardized methods that increase the contiguity and accuracy of vertebrate genome assemblies. This assembly resolves highly contiguous, somatically …

Chalcone Derivative Cx258 Suppresses Colorectal Cancer Via Inhibiting The Top2a/Wnt/Β-Catenin Signaling, Xi Chen, Xiaocheng Lv, Lijie Gao, Jiawei Liu, Wei Wang, Lichao Guo, Mykhaylo S. Frasinyuk, Wen Zhang, David S. Watt, Chunming Liu, Xifu Liu

Markey Cancer Center Faculty Publications

The deregulation in the Wnt/β-catenin signaling pathway is associated with many human cancers, particularly colorectal cancer (CRC) and, therefore, represents a promising target for drug development. We have screened over 300 semisynthetic and natural compounds using a Wnt reporter assay and identified a family of novel chalcone derivatives (CXs) that inhibited Wnt signaling and CRC cell proliferation. Among them, we selected CX258 for further in vitro and in vivo study to investigate the molecular mechanisms. We found that CX258 significantly inhibited β-catenin expression and nuclear translocation, inducing cell cycle arrest at the G2/M phase in CRC cells. Additionally, CX258 reduced …

Endogenous Glycoprotein Gpm6a Is Involved In Neurite Outgrowth In Rat Dorsal Root Ganglion Neurons, Gabriela I. Aparicio, Antonella León, Rocío Gutiérrez Fuster, Baylen Ravenscraft, Paula V. Monje, Camila Scorticati

Markey Cancer Center Faculty Publications

The peripheral nervous system (PNS) has a unique ability for self-repair. Dorsal root ganglion (DRG) neurons regulate the expression of different molecules, such as neurotrophins and their receptors, to promote axon regeneration after injury. However, the molecular players driving axonal regrowth need to be better defined. The membrane glycoprotein GPM6a has been described to contribute to neuronal development and structural plasticity in central-nervous-system neurons. Recent evidence indicates that GPM6a interacts with molecules from the PNS, although its role in DRG neurons remains unknown. Here, we characterized the expression of GPM6a in embryonic and adult DRGs by combining analysis of public …

Kegg_Pull: A Software Package For The Restful Access And Pulling From The Kyoto Encyclopedia Of Gene And Genomes, Erik D. Huckvale, Hunter N. B. Moseley

Markey Cancer Center Faculty Publications

Background: The Kyoto Encyclopedia of Genes and Genomes (KEGG) provides organized genomic, biomolecular, and metabolic information and knowledge that is reasonably current and highly useful for a wide range of analyses and modeling. KEGG follows the principles of data stewardship to be findable, accessible, interoperable, and reusable (FAIR) by providing RESTful access to their database entries via their web-accessible KEGG API. However, the overall FAIRness of KEGG is often limited by the library and software package support available in a given programming language. While R library support for KEGG is fairly strong, Python library support has been lacking. Moreover, there …

Attenuation Of Human Dmc1 Recombination Activities By Substitution Of A Conserved Residue, Melody Hayman

All Theses

Unrepaired DNA double strand breaks (DSB) are detrimental to the viability of the cell. The repair of DSBs can occur by a process called homologous recombination (HR). HR is used whenever the cell has a homologous template in the way of a homologous chromosome available. The process of HR during mitosis is different from meiotic HR. To initiate meiotic recombination, DSBs are formed and processed to allow proper chromosome segregation and ultimately genetic variation. Meiotic HR is mediated by the meiosis specific recombinase, DMC1. The DMC1 recombinase binds to the 3’ end of a newly resected DSB forming a nucleoprotein …

Editorial: Structure And Function Of Chloroplasts, Volume Iii, Hongbo Gao, Alistair J. Mccormick, Rebecca Roston, Yan Lu

Department of Biochemistry: Faculty Publications

Chloroplasts are endosymbiotic organelles derived from cyanobacteria. They have a double envelope membrane, including the outer envelope and the inner envelope. A complex membrane system, thylakoids, exists inside the chloroplast. It is the site of the light-dependent reactions of photosynthesis. The stroma is the main site of the carbon fixation reactions. Although photosynthesis is a very complicated process with many proteins involved, there are many other important processes that occur in chloroplasts, including the regulation of photosynthesis, the biogenesis and maintenance of the structures, carbohydrate, lipid, tetrapyrrole, amino acid, and isoprenoid metabolism, production of some phytohormones, production of specialized metabolites, …

Cholesterol In Class C Gpcrs: Role, Relevance, And Localization, Ugochi H. Isu, Shadi A. Badiee, Ehsaneh Khodadadi, Mahmoud Moradi

Chemistry & Biochemistry Faculty Publications and Presentations

G-protein coupled receptors (GPCRs), one of the largest superfamilies of cell-surface receptors, are heptahelical integral membrane proteins that play critical roles in virtually every organ system. G-protein-coupled receptors operate in membranes rich in cholesterol, with an imbalance in cholesterol level within the vicinity of GPCR transmembrane domains affecting the structure and/or function of many GPCRs, a phenomenon that has been linked to several diseases. These effects of cholesterol could result in indirect changes by altering the mechanical properties of the lipid environment or direct changes by binding to specific sites on the protein. There are a number of studies and …

Preparation And Characterization Of Salvia Triloba Extract And Evaluation Of Its Cytotoxic Effect On Bone Cancer Cell Line, Basma Hossam Abdelmonem

Theses and Dissertations

Background: Osteosarcoma is a tumor of mesenchymal origin characterized by uncontrolled production of immature osteoid tissue. It is more common in children and adults over the age of 65. Many studies reported the cytotoxic effect of many plant extracts, including Salvia triloba, on different cancer cell lines when used alone or in combination with other chemotherapeutic agents.

Methods: In our study, the methanolic extract obtained from the air-dried leaves of Salvia triloba leaves from Palestine was screened for its total phenolic and flavonoid contents. The major components of phenolics and flavonoids were detected using LC-QToF-MS technique. The two phenolics …

Probing Amyloid-Beta Protein Structure And Dynamics With A Selective Antibody, Shikha Grover

Dissertations

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder. The AD brain is characterized by significant neuronal loss and accumulation of insoluble fibrillar amyloid-β protein (Aβ) plaques and tau protein neurofibrillary tangles in the brain. However, over the last decade, many studies have shown that the neurodegenerative effect of Aβ may in fact be caused by various soluble oligomeric forms as opposed to the insoluble fibrils. Furthermore, the data suggest that a pre-fibrillar aggregated form, termed protofibrils, mediates direct neurotoxicity, and triggers a robust neuroinflammatory response.

Antibodies targeting the various conformation of Aβ are important therapeutic agents to prevent the progression …

Endogenous L- To D-Amino Acid Residue Isomerization Modulates Selectivity Between Distinct Neuropeptide Receptor Family Members, Baba M. Yussif, Cole V. Blasing, James W. Checco

Department of Biochemistry: Faculty Publications

The L- to D-amino acid residue isomerization of neuropeptides is an understudied post-translational modification found in animals across several phyla. Despite its physiological importance, little information is available regarding the impact of endogenous peptide isomerization on receptor recognition and activation. As a result, the full roles peptide isomerization play in biology are not well understood. Here, we identify that the Aplysia allatotropin-related peptide (ATRP) signaling system utilizes L- to D-residue isomerization of one amino acid residue in the neuropeptide ligand to modulate selectivity between two distinct G protein-coupled receptors (GPCRs). We first identified a novel receptor for ATRP that is …