scholarly journals Structural basis for auxiliary subunit KCTD16 regulation of the GABABreceptor

2019 ◽  
Vol 116 (17) ◽  
pp. 8370-8379 ◽  
Author(s):  
Hao Zuo ◽  
Ian Glaaser ◽  
Yulin Zhao ◽  
Igor Kurinov ◽  
Lidia Mosyak ◽  
...  
Keyword(s):  
Structural Basis ◽  
Functional Coupling ◽  
Girk Channels ◽  
Receptor Complexes ◽  
Binding Interface ◽  
Tetramerization Domain ◽  
High Resolution Structure ◽  
Inwardly Rectifying ◽  
The Brain ◽  
Oligomerization Domain

Metabotropic GABABreceptors mediate a significant fraction of inhibitory neurotransmission in the brain. Native GABABreceptor complexes contain the principal subunits GABAB1and GABAB2, which form an obligate heterodimer, and auxiliary subunits, known as potassium channel tetramerization domain-containing proteins (KCTDs). KCTDs interact with GABABreceptors and modify the kinetics of GABABreceptor signaling. Little is known about the molecular mechanism governing the direct association and functional coupling of GABABreceptors with these auxiliary proteins. Here, we describe the high-resolution structure of the KCTD16 oligomerization domain in complex with part of the GABAB2receptor. A single GABAB2C-terminal peptide is bound to the interior of an open pentamer formed by the oligomerization domain of five KCTD16 subunits. Mutation of specific amino acids identified in the structure of the GABAB2–KCTD16 interface disrupted both the biochemical association and functional modulation of GABABreceptors and G protein-activated inwardly rectifying K+channel (GIRK) channels. These interfacial residues are conserved among KCTDs, suggesting a common mode of KCTD interaction with GABABreceptors. Defining the binding interface of GABABreceptor and KCTD reveals a potential regulatory site for modulating GABAB-receptor function in the brain.

scholarly journals Structural basis of GIRK2 channel modulation by cholesterol and PIP2

2020 ◽  
Author(s):  
Yamuna Kalyani Mathiharan ◽  
Ian W. Glaaser ◽  
Yulin Zhao ◽  
Michael J. Robertson ◽  
Georgios Skiniotis ◽  
...  
Keyword(s):  
G Protein ◽  
Transmembrane Domain ◽  
Structural Data ◽  
Structural Basis ◽  
Girk Channels ◽  
Channel Modulation ◽  
Cryo Electron Microscopy ◽  
Cellular Excitability ◽  
Cholesteryl Hemisuccinate ◽  
Inwardly Rectifying

ABSTRACTG protein-gated inwardly rectifying potassium (GIRK) channels play important roles in controlling cellular excitability in the heart and brain. While structural data begin to unravel the molecular basis for G protein and alcohol dependent activation of GIRK channels, little is known about the modulation by cholesterol. Here, we present cryo-electron microscopy (cryoEM) structures of GIRK2 in the presence and absence of the cholesterol analog cholesteryl hemisuccinate (CHS), and PIP2. The structures and their comparison reveal that CHS binds near PIP2 in lipid-facing hydrophobic pockets of the transmembrane domain (TMD). CHS potentiates the effects of PIP2, which stabilizes the inter-domain region and promotes the engagement of the cytoplasmic domain (CTD) onto the transmembrane region. The results suggest that CHS acts as a positive allosteric modulator and identify novel therapeutic sites for modulating GIRK channels in the brain.

scholarly journals Structural basis for ALK2/BMPR2 receptor complex signaling through kinase domain oligomerization

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Christopher Agnew ◽  
Pelin Ayaz ◽  
Risa Kashima ◽  
Hanna S. Loving ◽  
Prajakta Ghatpande ◽  
...  
Keyword(s):  
Md Simulations ◽  
Kinase Domain ◽  
Structural Basis ◽  
Type I ◽  
Type Ii ◽  
Exchange Mass Spectrometry ◽  
Receptor Complexes ◽  
Bmp Receptors ◽  
Morphogenetic Protein ◽  
Smad Proteins

AbstractUpon ligand binding, bone morphogenetic protein (BMP) receptors form active tetrameric complexes, comprised of two type I and two type II receptors, which then transmit signals to SMAD proteins. The link between receptor tetramerization and the mechanism of kinase activation, however, has not been elucidated. Here, using hydrogen deuterium exchange mass spectrometry (HDX-MS), small angle X-ray scattering (SAXS) and molecular dynamics (MD) simulations, combined with analysis of SMAD signaling, we show that the kinase domain of the type I receptor ALK2 and type II receptor BMPR2 form a heterodimeric complex via their C-terminal lobes. Formation of this dimer is essential for ligand-induced receptor signaling and is targeted by mutations in BMPR2 in patients with pulmonary arterial hypertension (PAH). We further show that the type I/type II kinase domain heterodimer serves as the scaffold for assembly of the active tetrameric receptor complexes to enable phosphorylation of the GS domain and activation of SMADs.

scholarly journals Visualization of Head–Head Interactions in the Inhibited State of Smooth Muscle Myosin

1999 ◽  
Vol 147 (7) ◽  
pp. 1385-1390 ◽  
Author(s):  
Thomas Wendt ◽  
Dianne Taylor ◽  
Terri Messier ◽  
Kathleen M. Trybus ◽  
Kenneth A. Taylor
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Myosin ◽  
Intramolecular Interactions ◽  
Actin Binding ◽  
Structural Basis ◽  
Binding Interface ◽  
Structural Differences ◽  
Muscle Myosin ◽  
Positively Charged ◽  
Phosphoryla Tion

The structural basis for the phosphoryla- tion-dependent regulation of smooth muscle myosin ATPase activity was investigated by forming two- dimensional (2-D) crystalline arrays of expressed unphosphorylated and thiophosphorylated smooth muscle heavy meromyosin (HMM) on positively charged lipid monolayers. A comparison of averaged 2-D projections of both forms at 2.3-nm resolution reveals distinct structural differences. In the active, thiophosphorylated form, the two heads of HMM interact intermolecularly with adjacent molecules. In the unphosphorylated or inhibited state, intramolecular interactions position the actin-binding interface of one head onto the converter domain of the second head, thus providing a mechanism whereby the activity of both heads could be inhibited.

Cannabidiol Has a Unique Effect on Global Brain Activity: A Pharmacological, Functional MRI Study in Awake Mice 

2021 ◽  
Author(s):  
Aymen Sadaka ◽  
Ana Ozuna ◽  
Richard Ortiz ◽  
Praveen Kulkarni ◽  
Clare Johnson ◽  
...  
Keyword(s):  
Prefrontal Cortex ◽  
Brain Activity ◽  
Stress Disorders ◽  
Functional Coupling ◽  
Specific Information ◽  
Imaging Data ◽  
Post Traumatic Stress ◽  
Brain Areas ◽  
Dose Dependent ◽  
The Brain

Abstract Background: The phytocannabinoid cannabidiol (CBD) is a potential treatment for post-traumatic stress disorders. How does CBD interact with the brain to alter behavior? We hypothesized that CBD would produce a dose-dependent reduction in brain activity and functional coupling in neural circuitry associated with fear and defense. Methods: During the scanning session awake mice were given vehicle or CBD (3, 10, or 30 mg/kg I.P.) and imaged for 10 min post treatment. Mice were also treated with the 10 mg/kg dose of CBD and imaged one hr later for resting state BOLD functional connectivity (rsFC). Imaging data were registered to a 3D MRI mouse atlas providing site-specific information on 138 different brain areas. Blood samples were collected for CBD measurements.Results: CBD produced a dose-dependent polarization of activation along the rostral-caudal axis of the brain. The olfactory bulb and prefrontal cortex showed an increase in positive BOLD whereas the brainstem and cerebellum showed a decrease in BOLD signal. This negative BOLD affected many areas connected to the ascending reticular activating system (ARAS). The ARAS was decoupled to much of the brain but was hyperconnected to the olfactory system and prefrontal cortex. The pattern of ARAS connectivity closely overlapped with brain areas showing high levels N-acyl-phosphatidylethanolamines-specific phospholipase D (NAPE-PLD) messenger RNA.Conclusion: The CBD-induced decrease in ARAS activity is consistent with an emerging literature suggesting that CBD reduces autonomic arousal under conditions of emotional and physical stress. The putative target and mechanism of action is NAPE-PLD the enzyme responsible for the biosynthesis of lipid signaling molecules like anandamide.

scholarly journals Scale-Free Coupled Dynamics in Brain Networks Captured by Bivariate Focus-Based Multifractal Analysis

2021 ◽  
Vol 11 ◽  
Author(s):  
Orestis Stylianou ◽  
Frigyes Samuel Racz ◽  
Andras Eke ◽  
Peter Mukli
Keyword(s):  
Resting State ◽  
Functional Coupling ◽  
Dependent Manner ◽  
Coupled Dynamics ◽  
Scale Free ◽  
Neural Processes ◽  
Eeg Recordings ◽  
Cortical Regions ◽  
The Brain

While most connectivity studies investigate functional connectivity (FC) in a scale-dependent manner, coupled neural processes may also exhibit broadband dynamics, manifesting as power-law scaling of their measures of interdependence. Here we introduce the bivariate focus-based multifractal (BFMF) analysis as a robust tool for capturing such scale-free relations and use resting-state electroencephalography (EEG) recordings of 12 subjects to demonstrate its performance in reconstructing physiological networks. BFMF was employed to characterize broadband FC between 62 cortical regions in a pairwise manner, with all investigated connections being tested for true bivariate multifractality. EEG channels were also grouped to represent the activity of six resting-state networks (RSNs) in the brain, thus allowing for the analysis of within- and between- RSNs connectivity, separately. Most connections featured true bivariate multifractality, which could be attributed to the genuine scale-free coupling of neural dynamics. Bivariate multifractality showed a characteristic topology over the cortex that was highly concordant among subjects. Long-term autocorrelation was higher in within-RSNs, while the degree of multifractality was generally found stronger in between-RSNs connections. These results offer statistical evidence of the bivariate multifractal nature of functional coupling in the brain and validate BFMF as a robust method to capture such scale-independent coupled dynamics.

scholarly journals Structural basis for recognition of human 7SK long noncoding RNA by the La-related protein Larp7

2018 ◽  
Vol 115 (28) ◽  
pp. E6457-E6466 ◽  
Author(s):  
Catherine D. Eichhorn ◽  
Yuan Yang ◽  
Lucas Repeta ◽  
Juli Feigon
Keyword(s):  
Noncoding Rna ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Transcription Elongation ◽  
Structural Basis ◽  
Titration Calorimetry ◽  
Rna Recognition Motif ◽  
Related Protein ◽  
Binding Interface ◽  
And Function

The La and the La-related protein (LARP) superfamily is a diverse class of RNA binding proteins involved in RNA processing, folding, and function. Larp7 binds to the abundant long noncoding 7SK RNA and is required for 7SK ribonucleoprotein (RNP) assembly and function. The 7SK RNP sequesters a pool of the positive transcription elongation factor b (P-TEFb) in an inactive state; on release, P-TEFb phosphorylates RNA Polymerase II to stimulate transcription elongation. Despite its essential role in transcription, limited structural information is available for the 7SK RNP, particularly for protein–RNA interactions. Larp7 contains an N-terminal La module that binds UUU-3′OH and a C-terminal atypical RNA recognition motif (xRRM) required for specific binding to 7SK and P-TEFb assembly. Deletion of the xRRM is linked to gastric cancer in humans. We report the 2.2-Å X-ray crystal structure of the human La-related protein group 7 (hLarp7) xRRM bound to the 7SK stem-loop 4, revealing a unique binding interface. Contributions of observed interactions to binding affinity were investigated by mutagenesis and isothermal titration calorimetry. NMR 13C spin relaxation data and comparison of free xRRM, RNA, and xRRM–RNA structures show that the xRRM is preordered to bind a flexible loop 4. Combining structures of the hLarp7 La module and the xRRM–7SK complex presented here, we propose a structural model for Larp7 binding to the 7SK 3′ end and mechanism for 7SK RNP assembly. This work provides insight into how this domain contributes to 7SK recognition and assembly of the core 7SK RNP.

The skull

2013 ◽  
Author(s):  
Martin E. Atkinson
Keyword(s):  
Soft Tissues ◽  
Clinical Importance ◽  
Dental Students ◽  
Structural Basis ◽  
Facial Skeleton ◽  
Lower Jaw ◽  
Temporomandibular Joints ◽  
Maxilla And Mandible ◽  
And Function ◽  
The Brain

Dental students and practitioners require a sound knowledge of the structure, growth, and development of the skull as a whole. The structure of the skull can be examined and studied more efficiently if you have access to a dried skull or one of the very good plastic replica skulls which are now available; you can identify the structures on the diagrams accompanying the following descriptions and examine a skull at the same time to appreciate the size and relationships of individual components. This chapter outlines the basic principles of the development and structure of the skull and includes some reference to individual bones where this makes understanding easier. The more detailed aspects of particular regions of the skull will be covered in the appropriate chapter describing the whole anatomy of that region; it is much easier to learn the parts of the skull in context of overall structure and function rather than learning a long list of bones, foramina, and muscle attachments in isolation from the related soft tissue structures. Only the maxilla and mandible which are bones of significant clinical importance are described as separate bones. As already demonstrated in Chapter 20, the skull is the structural basis f or the anatomy of the head. The skull has many functions. • It encloses and protects the brain. • It provides protective capsules for the eyes and middle and inner ear. • It forms the skeleton of the entrances to the respiratory and gastrointestinal tracts (GIT) through the nose and mouth, respectively. Those skull components that form the entrance to the GIT also house and support the teeth and soft tissues of the oral region as part of this function. As already outlined in Chapter 20, the skull is made up of several bones joined together to form the cranium which articulates with the separate mandible forming the lower jaw at the temporomandibular joints. The cranium specifically refers to the skull without the mandible; the terms ‘skull’ and ‘cranium’ are not strictly synonymous but they are frequently used as though they are. The cranium can be subdivided into the braincase enclosing the brain and the facial skeleton.

scholarly journals Developmentally regulated expression of CD3 components independent of clonotypic T cell antigen receptor complexes on immature thymocytes.

1994 ◽  
Vol 180 (4) ◽  
pp. 1375-1382 ◽  
Author(s):  
D L Wiest ◽  
K P Kearse ◽  
E W Shores ◽  
A Singer
Keyword(s):  
T Cells ◽  
T Cell ◽  
Biochemical Characterization ◽  
Severe Combined Immunodeficiency ◽  
Structural Basis ◽  
Thymocyte Development ◽  
Antibody Treatment ◽  
Receptor Complexes ◽  
Stage Of Development ◽  
Immature Thymocytes

CD3 signal transducing proteins are thought to be expressed on the surface of T cells only as part of clonotypic T cell receptor (TCR) complexes. Contrary to this paradigm, the present study describes surface expression of CD3 proteins independently of clonotypic TCR complexes, but only on immature thymocytes. Such novel clonotype-independent CD3 (CIC) complexes are composed primarily of CD3 gamma epsilon and secondarily of CD3 delta epsilon heterodimers that are independent of one another and are expressed on the cell surface in association with an unknown 90-100 kD protein termed CD3-associated protein (CD3AP). CIC complexes are expressed in normal mice on early thymocytes through the CD4+CD8+ stage of development, but not on mature peripheral T cells. Furthermore, CIC complexes are expressed by both TCR- severe combined immunodeficiency (SCID) thymocytes and thymoma cell lines, in the absence of any clonotypic chains. The isolation and biochemical characterization of surface CIC complexes provides a structural basis for the signaling effects of anti-CD3 epsilon antibody treatment in early thymocyte development.

scholarly journals Structures of ribosome-bound initiation factor 2 reveal the mechanism of subunit association

2016 ◽  
Vol 2 (3) ◽  
pp. e1501502 ◽  
Author(s):  
Thiemo Sprink ◽  
David J. F. Ramrath ◽  
Hiroshi Yamamoto ◽  
Kaori Yamamoto ◽  
Justus Loerke ◽  
...  
Keyword(s):  
Translation Initiation ◽  
Protein Biosynthesis ◽  
Initiation Factor ◽  
Structural Basis ◽  
Initiation Complex ◽  
Cryo Electron Microscopy ◽  
Initiation Factor 2 ◽  
High Resolution Structure ◽  
Guanosine Triphosphatase ◽  
Resolution Structure

Throughout the four phases of protein biosynthesis—initiation, elongation, termination, and recycling—the ribosome is controlled and regulated by at least one specified translational guanosine triphosphatase (trGTPase). Although the structural basis for trGTPase interaction with the ribosome has been solved for the last three steps of translation, the high-resolution structure for the key initiation trGTPase, initiation factor 2 (IF2), complexed with the ribosome, remains elusive. We determine the structure of IF2 complexed with a nonhydrolyzable guanosine triphosphate analog and initiator fMet-tRNAiMet in the context of the Escherichia coli ribosome to 3.7-Å resolution using cryo-electron microscopy. The structural analysis reveals previously unseen intrinsic conformational modes of the 70S initiation complex, establishing the mutual interplay of IF2 and initator transfer RNA (tRNA) with the ribsosome and providing the structural foundation for a mechanistic understanding of the final steps of translation initiation.

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