Src family kinases are maintained in an assembled, inactive conformation by intramolecular interactions of their SH2 and SH3 domains. Full catalytic activity requires release of these restraints as well as phosphorylation of Tyr-416 in the activation loop. In previous structures of inactive Src kinases, Tyr-416 and flanking residues are disordered. We report here four additional c-Src structures in which this segment adopts an ordered but inhibitory conformation. The ordered activation loop forms an alpha helix that stabilizes the inactive conformation of the kinase domain, blocks the peptide substrate-binding site, and prevents Tyr-416 phosphorylation. Disassembly of the regulatory domains, induced by SH2 or SH3 ligands, or by dephosphorylation of Tyr-527, could lead to exposure and phosphorylation of Tyr-416.
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Front Parasitol
April 2024
Institut für Parasitologie, Biomedizinisches Forschungszentrum Seltersberg (BFS), Justus Liebig Universitaet Giessen, Giessen, Germany.
Introduction: Schistosomiasis has for many years relied on a single drug, praziquantel (PZQ) for treatment of the disease. Immense efforts have been invested in the discovery of protein kinase (PK) inhibitors; however, given that the majority of PKs are still not targeted by an inhibitor with a useful level of selectivity, there is a compelling need to expand the chemical space available for synthesizing new, potent, and selective PK inhibitors. Small-molecule inhibitors targeting the ATP pocket of the catalytic domain of PKs have the potential to become drugs devoid of (major) side effects, particularly if they bind selectively.
View Article and Find Full Text PDFMethods Mol Biol
January 2025
Estrella Mountain Community College, Phoenix, AZ, USA.
Vacuole fusion is driven by SNARE proteins that require activation-or priming-by the AAA+ protein Sec18 (NSF) before they can bring membranes together and trigger the merger of two bilayers into a continuous membrane. Sec18 resides on vacuoles prior to engaging inactive cis-SNARE complexes through its interaction with the regulatory lipid phosphatidic acid (PA). Binding PA causes Sec18 to undergo large conformational changes that keeps it bound to the membrane, thus precluding its interactions with SNAREs.
View Article and Find Full Text PDFNat Commun
January 2025
Department of Plant Molecular Biology and Physiology, Albrecht-von-Haller Institute for Plant Sciences, Georg-August-University Göttingen, Julia-Lermontowa-Weg 3, 37077, Göttingen, Germany.
Class I glutaredoxins (GRXs) are nearly ubiquitous proteins that catalyse the glutathione (GSH)-dependent reduction of mainly glutathionylated substrates. In land plants, a third class of GRXs has evolved (class III). Class III GRXs regulate the activity of TGA transcription factors through yet unexplored mechanisms.
View Article and Find Full Text PDFNucleic Acids Res
January 2025
Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan.
Oscillation of the active form of the initiator protein DnaA (ATP-DnaA) allows for the timely regulation for chromosome replication. After initiation, DnaA-bound ATP is hydrolyzed, producing inactive ADP-DnaA. For the next round of initiation, ADP-DnaA interacts with the chromosomal locus DARS2 bearing binding sites for DnaA, a DNA-bending protein IHF, and a transcription activator Fis.
View Article and Find Full Text PDFInt J Mol Sci
December 2024
Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan 250012, China.
G protein-coupled receptors (GPCRs) play essential roles in numerous physiological processes and are key targets for drug development. Among them, adhesion GPCRs (aGPCRs) stand out for their unique domain structures and diverse functions. ADGRG2 is a member of the aGPCR family and is involved in the regulation of various systems in the human body, including reproductive, nervous, cardiovascular, and endocrine systems.
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