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The abscisic acid (ABA) signaling pathway is regulated by clade A type 2C protein phosphatases (PP2CAs) in plants. In the presence of ABA, PP2Cs release stress/ABA-activated protein kinases by binding to ABA-bound receptors (PYL/RCARs) for activation. Although the wedging tryptophan in PP2Cs is critical in the interaction with PYL/RCARs in Arabidopsis and rice, it remains elusive as to how other interface regions are involved in the interaction. Here, we report the identification of a conserved region on PP2Cs, termed the VxGΦL motif, which modulates the interaction with PYL/RCARs through its second and fourth residues. The effects of the second and fourth residues on the interaction of OsPP2C50 with several OsPYL/RCAR proteins were investigated by systematic mutagenesis. One OsPP2C50 mutant, VFGML ("FM") mutant, lowered the affinity to OsPYL/RCAR3 by ∼15-fold in comparison with the wild-type. Comparison of the crystal structures of wild-type OsPP2C50:ABA:OsPYL/RCAR3 with those composed of FM mutant revealed local conformational changes near the VxGΦL motif, further supported by hydrogen-deuterium exchange mass spectrometry. In rice protoplasts, ABA signaling was altered by mutations in the VxGΦL motif. Transgenic Arabidopsis plants overexpressing OsPP2C50 and OsPP2C50FM showed altered ABA sensitivity. Taken together, the VxGΦL motif of PP2Cs appears to modulate the affinity of PP2Cs with PYL/RCARs and thus likely to alter the ABA signaling, leading to the differential sensitivity to ABA in planta.
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http://dx.doi.org/10.1016/j.molp.2017.08.003 | DOI Listing |
Physiology (Bethesda)
September 2025
Departments of Ophthalmology and Medicine, Stanford Cardiovascular Institute, Stanford University, Palo Alto, CA 94304.
Canonical activation of G-protein coupled receptors (GPCRs) by hormone binding occurs at the plasma membrane, resulting in the diffusion of second messengers to intracellular effector sites throughout the cell. In contrast, recent evidence suggests that functional GPCRs can induce signaling from distinct intracellular domains, contributing to specificity in signaling. Functional adrenergic receptors have been identified at intracellular sites in the cardiac myocyte such as endosomes, the sarcoplasmic reticulum, the Golgi and the inner nuclear membrane.
View Article and Find Full Text PDFSci Adv
September 2025
Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA.
Integrins bind ligands between their alpha (α) and beta (β) subunits and transmit signals through conformational changes. Early in chordate evolution, some α subunits acquired an "inserted" (I) domain that expanded integrin's ligand-binding repertoire but obstructed the ancestral ligand pocket, seemingly blocking conventional integrin activation. Here, we compare cryo-electron microscopy structures of apo and ligand-bound states of the I domain-containing αEβ integrin and the I domain-lacking αβ integrin to illuminate how the I domain intrinsically mimics an extrinsic ligand to preserve integrin function.
View Article and Find Full Text PDFSci Transl Med
September 2025
Vaccine Research Center (VRC), National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Human B cell immunity to the influenza hemagglutinin (HA) stem, a universal vaccine target, is often stereotyped and immunogenetically restricted, posing hurdles to study outside of humans. Here, we show that cynomolgus macaques vaccinated with an HA stem immunogen elicit humanlike public B cell lineages targeting two major conserved sites of vulnerability, the central stem and anchor epitopes. Central stem antibodies were predominantly derived from V1-138, the macaque homolog of human V1-69, a V gene preferentially used in human central stem broadly neutralizing antibodies (bnAbs).
View Article and Find Full Text PDFAm J Physiol Cell Physiol
September 2025
Division of Gastroenterology & Hepatology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Chronic diarrhea is a frequent gastrointestinal complication in both type 1 (T1D) and type 2 diabetes (T2D), although the underlying mechanisms differ: T1D is linked to autonomic neuropathy and disrupted transporter regulation, while T2D is often linked to medications and intestinal inflammation. Using streptozotocin-induced mouse models of T1D and T2D, we observed increased luminal fluid in the small intestine of both. Given the role of Na⁺/H⁺ exchanger 3 (NHE3) in fluid absorption and its loss in most diarrheal diseases, we examined NHE3 expression across intestinal segments.
View Article and Find Full Text PDFBioinformatics
September 2025
Computational Health Center, Helmholtz Center Munich, Neuherberg, 85764, Germany.
Motivation: Recent pandemics have revealed significant gaps in our understanding of viral pathogenesis, exposing an urgent need for methods to identify and prioritize key host proteins (host factors) as potential targets for antiviral treatments. De novo generation of experimental datasets is limited by their heterogeneity, and for looming future pandemics, may not be feasible due to limitations of experimental approaches.
Results: Here we present TransFactor, a computational framework for predicting and prioritizing candidate host factors using only protein sequence data.