scholarly journals Intramolecular domain dynamics regulate synaptic MAGUK protein interactions

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Nils Rademacher ◽  
Benno Kuropka ◽  
Stella-Amrei Kunde ◽  
Markus C Wahl ◽  
Christian Freund ◽  
...  
Keyword(s):  
Complex Formation ◽  
Protein Interactions ◽  
Hippocampal Neurons ◽  
Protein Complexes ◽  
Pdz Domain ◽  
Domain Architecture ◽  
Protein Subunit ◽  
Functional Changes ◽  
The Third ◽  
Domain Dynamics

PSD-95 MAGUK family scaffold proteins are multi-domain organisers of synaptic transmission that contain three PDZ domains followed by an SH3-GK domain tandem. This domain architecture allows coordinated assembly of protein complexes composed of neurotransmitter receptors, synaptic adhesion molecules and downstream signalling effectors. Here we show that binding of monomeric CRIPT-derived PDZ3 ligands to the third PDZ domain of PSD-95 induces functional changes in the intramolecular SH3-GK domain assembly that influence subsequent homotypic and heterotypic complex formation. We identify PSD-95 interactors that differentially bind to the SH3-GK domain tandem depending on its conformational state. Among these interactors, we further establish the heterotrimeric G protein subunit Gnb5 as a PSD-95 complex partner at dendritic spines of rat hippocampal neurons. The PSD-95 GK domain binds to Gnb5, and this interaction is triggered by CRIPT-derived PDZ3 ligands binding to the third PDZ domain of PSD-95, unraveling a hierarchical binding mechanism of PSD-95 complex formation.

scholarly journals Intramolecular domain dynamics regulate synaptic MAGUK protein interactions

2018 ◽  
Author(s):  
Nils Rademacher ◽  
Benno Kuropka ◽  
Stella-Amrei Kunde ◽  
Markus C. Wahl ◽  
Christian Freund ◽  
...  
Keyword(s):  
Complex Formation ◽  
Protein Interactions ◽  
Protein Complexes ◽  
Pdz Domain ◽  
Domain Architecture ◽  
Cytoskeletal Proteins ◽  
Protein Subunit ◽  
Functional Changes ◽  
The Third ◽  
Domain Dynamics

AbstractPSD-95 MAGUK family scaffold proteins are multi-domain organisers of synaptic transmission that contain three PDZ domains followed by an SH3-GK domain tandem. This domain architecture allows coordinated assembly of protein complexes composed of neurotransmitter receptors, synaptic adhesion molecules, cytoskeletal proteins and downstream signalling effectors. Here we show that binding of monomeric PDZ3 ligands to the third PDZ domain of PSD-95 induces functional changes in the intramolecular SH3-GK domain assembly that influence subsequent homotypic and heterotypic complex formation. We identify PSD-95 interactors that differentially bind to the SH3-GK domain tandem depending on its conformational state. Among these interactors we further establish the heterotrimeric G protein subunit Gnb5 as a PSD-95 complex partner at dendritic spines. The PSD-95 GK domain binds to Gnb5 and this interaction is triggered by PDZ3 ligands binding to the third PDZ domain of PSD-95, unraveling a hierarchical binding mechanism of PSD-95 complex formation.

scholarly journals Binding of recombinant interleukin-1 beta to the third complement component and alpha 2-macroglobulin after activation of serum by immune complexes

Blood ◽  
1990 ◽  
Vol 75 (12) ◽  
pp. 2388-2395 ◽  
Author(s):  
W Borth ◽  
A Urbanski ◽  
R Prohaska ◽  
M Susanj ◽  
TA Luger
Keyword(s):  
Complex Formation ◽  
Immune Complexes ◽  
Protein Complexes ◽  
Interleukin 1 ◽  
Complement Component ◽  
Interleukin 1 Beta ◽  
Thiol Groups ◽  
Thiol Ester ◽  
The Third ◽  
Sds Page

Abstract Activation of human normal serum with tetanus/antitetanus immune complexes (TAT-IC) resulted in increased binding of 125I-labeled interleukin-1 beta (IL-1 beta) to serum factors, as opposed to untreated serum. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) followed by autoradiography showed labeling of two large molecular mass factors of an apparent molecular weight (Mr) of 200,000 and 400,000, respectively. These complexes could be dissociated by reduction. No complexes were formed when reducing compounds were added to serum-TAT-IC-125I-IL-1 beta mixtures. Complex formation was largely prevented by alkylating compounds. Molecular sieve chromatography of TAT-IC-activated serum confirmed that 125I-IL-1 beta became bound to high Mr serum proteins. Fractions containing high molecular 125I-IL-1 serum protein complexes partially retained IL-1- like activity since they induced proliferation of an IL-1-dependent murine T helper (D10G4) cell lineage. The 125I-IL-1 beta binding factors could be immunoprecipitated from TAT-IC-activated serum 125I-IL- 1 beta solutions by antisera to alpha 2-macroglobulin (alpha 2M) or to the third complement component (C3). SDS-PAGE of the immunoprecipitates showed radioactive bands corresponding to the expected Mr resulting from complex formation between 125I-IL-1 beta and these two proteins. Treatment of purified plasma alpha 2M and C3 with trypsin or activation with methylamine, which causes cleavage of the internal thiol ester and the appearance of free thiol groups in these proteins, mediated binding of 125I-IL-1 beta to alpha 2M and C3b. The results suggest that cleavage of the internal thiol ester in C3 and alpha 2M makes these plasma proteins susceptible to binding of 125I-IL-1 beta and that free thiol groups do play a role in the formation of 125I-IL-1 beta plasma protein complexes. Activated C3 and alpha 2M may function as IL-1 beta carrier proteins in biologic fluids, in addition to their other physiologic roles.

scholarly journals Slitrk2 controls excitatory synapse development via PDZ-mediated protein interactions

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Kyung Ah Han ◽  
Jinhu Kim ◽  
Hyeonho Kim ◽  
Dongwook Kim ◽  
Dongseok Lim ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Intracellular Signaling ◽  
Hippocampal Neurons ◽  
Pdz Domain ◽  
Protein Tyrosine Phosphatases ◽  
Excitatory Synapse ◽  
Receptor Protein ◽  
Binding Motif ◽  
Synapse Development

AbstractMembers of the Slitrk (Slit- and Trk-like protein) family of synaptic cell-adhesion molecules control excitatory and inhibitory synapse development through isoform-dependent extracellular interactions with leukocyte common antigen-related receptor protein tyrosine phosphatases (LAR-RPTPs). However, how Slitrks participate in activation of intracellular signaling pathways in postsynaptic neurons remains largely unknown. Here we report that, among the six members of the Slitrk family, only Slitrk2 directly interacts with the PDZ domain-containing excitatory scaffolds, PSD-95 and Shank3. The interaction of Slitrk2 with PDZ proteins is mediated by the cytoplasmic COOH-terminal PDZ domain-binding motif (Ile-Ser-Glu-Leu), which is not found in other Slitrks. Mapping analyses further revealed that a single PDZ domain of Shank3 is responsible for binding to Slitrk2. Slitrk2 forms in vivo complexes with membrane-associated guanylate kinase (MAGUK) family proteins in addition to PSD-95 and Shank3. Intriguingly, in addition to its role in synaptic targeting in cultured hippocampal neurons, the PDZ domain-binding motif of Slitrk2 is required for Slitrk2 promotion of excitatory synapse formation, transmission, and spine development in the CA1 hippocampal region. Collectively, our data suggest a new molecular mechanism for conferring isoform-specific regulatory actions of the Slitrk family in orchestrating intracellular signal transduction pathways in postsynaptic neurons.

scholarly journals Molecular basis for protein–protein interactions

2021 ◽  
Vol 17 ◽  
pp. 1-10
Author(s):  
Brandon Charles Seychell ◽  
Tobias Beck
Keyword(s):  
Complex Formation ◽  
Molecular Interactions ◽  
Protein Interactions ◽  
Molecular Basis ◽  
Current Knowledge ◽  
Protein Complexes ◽  
Deep Understanding ◽  
Protein Protein Interactions ◽  
Protein Complex Formation ◽  
Characterisation Methods

This minireview provides an overview on the current knowledge of protein–protein interactions, common characterisation methods to characterise them, and their role in protein complex formation with some examples. A deep understanding of protein–protein interactions and their molecular interactions is important for a number of applications, including drug design. Protein–protein interactions and their discovery are thus an interesting avenue for understanding how protein complexes, which make up the majority of proteins, work.

scholarly journals Cryo-EM structure of an activated GPCR-G protein complex in lipid nanodiscs

2020 ◽  
Author(s):  
Gerhard Wagner ◽  
Meng Zhang ◽  
Miao Gui ◽  
Zi-Fu Wang ◽  
Christoph Gorgulla ◽  
...  
Keyword(s):  
Complex Formation ◽  
G Protein ◽  
Lipid Bilayer ◽  
Lipid Bilayers ◽  
Protein Interactions ◽  
Protein Complex ◽  
Lipid Membrane ◽  
Protein Complexes ◽  
Structural Basis ◽  
Downstream Signaling

Abstract G protein coupled receptors (GPCRs) are the largest superfamily of transmembrane proteins and the targets of over 30% of currently marketed pharmaceuticals. Although several structures have been solved for GPCR-G protein complexes, structural studies of the complex in a physiological lipid membrane environment are lacking. Here, we report cryo-EM structures of lipid bilayer-bound complexes of neurotensin, neurotensin receptor 1, and Gai1b1g1 protein in two conformational states, resolved to 4.1 and 4.2 Å resolution. The structures were determined in lipid bilayer without any stabilizing antibodies/nanobodies, and thus provide a native-like platform for understanding the structural basis of GPCR-G protein complex formation. Our structures reveal an extended network of protein-protein interactions at the GPCR-G protein interface compared to in detergent micelles, defining roles for the lipid membrane in modulating the structure and dynamics of complex formation, and providing a molecular explanation for the stronger interaction between GPCR and G protein in lipid bilayers. We propose a detailed allosteric mechanism for GDP release, providing new insights into the activation of G proteins for downstream signaling.

scholarly journals Binding of recombinant interleukin-1 beta to the third complement component and alpha 2-macroglobulin after activation of serum by immune complexes

Blood ◽  
1990 ◽  
Vol 75 (12) ◽  
pp. 2388-2395
Author(s):  
W Borth ◽  
A Urbanski ◽  
R Prohaska ◽  
M Susanj ◽  
TA Luger
Keyword(s):  
Complex Formation ◽  
Immune Complexes ◽  
Protein Complexes ◽  
Interleukin 1 ◽  
Complement Component ◽  
Interleukin 1 Beta ◽  
Thiol Groups ◽  
Thiol Ester ◽  
The Third ◽  
Sds Page

Activation of human normal serum with tetanus/antitetanus immune complexes (TAT-IC) resulted in increased binding of 125I-labeled interleukin-1 beta (IL-1 beta) to serum factors, as opposed to untreated serum. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) followed by autoradiography showed labeling of two large molecular mass factors of an apparent molecular weight (Mr) of 200,000 and 400,000, respectively. These complexes could be dissociated by reduction. No complexes were formed when reducing compounds were added to serum-TAT-IC-125I-IL-1 beta mixtures. Complex formation was largely prevented by alkylating compounds. Molecular sieve chromatography of TAT-IC-activated serum confirmed that 125I-IL-1 beta became bound to high Mr serum proteins. Fractions containing high molecular 125I-IL-1 serum protein complexes partially retained IL-1- like activity since they induced proliferation of an IL-1-dependent murine T helper (D10G4) cell lineage. The 125I-IL-1 beta binding factors could be immunoprecipitated from TAT-IC-activated serum 125I-IL- 1 beta solutions by antisera to alpha 2-macroglobulin (alpha 2M) or to the third complement component (C3). SDS-PAGE of the immunoprecipitates showed radioactive bands corresponding to the expected Mr resulting from complex formation between 125I-IL-1 beta and these two proteins. Treatment of purified plasma alpha 2M and C3 with trypsin or activation with methylamine, which causes cleavage of the internal thiol ester and the appearance of free thiol groups in these proteins, mediated binding of 125I-IL-1 beta to alpha 2M and C3b. The results suggest that cleavage of the internal thiol ester in C3 and alpha 2M makes these plasma proteins susceptible to binding of 125I-IL-1 beta and that free thiol groups do play a role in the formation of 125I-IL-1 beta plasma protein complexes. Activated C3 and alpha 2M may function as IL-1 beta carrier proteins in biologic fluids, in addition to their other physiologic roles.

scholarly journals Protein-Protein Interactions in the Complex between the Enhancer Binding Protein NIFA and the Sensor NIFL fromAzotobacter vinelandii

2001 ◽  
Vol 183 (4) ◽  
pp. 1359-1368 ◽  
Author(s):  
Tracy Money ◽  
Jason Barrett ◽  
Ray Dixon ◽  
Sara Austin
Keyword(s):  
Complex Formation ◽  
Protein Interactions ◽  
Azotobacter Vinelandii ◽  
Protein Complexes ◽  
Binding Protein ◽  
Limited Proteolysis ◽  
Regulatory System ◽  
Terminal Domain ◽  
Enhancer Binding Protein

ABSTRACT The enhancer binding protein NIFA and the sensor protein NIFL fromAzotobacter vinelandii comprise an atypical two-component regulatory system in which signal transduction occurs via complex formation between the two proteins rather than by the phosphotransfer mechanism, which is characteristic of orthodox systems. The inhibitory activity of NIFL towards NIFA is stimulated by ADP binding to the C-terminal domain of NIFL, which bears significant homology to the histidine protein kinase transmitter domains. Adenosine nucleotides, particularly MgADP, also stimulate complex formation between NIFL and NIFA in vitro, allowing isolation of the complex by cochromatography. Using limited proteolysis of the purified proteins, we show here that changes in protease sensitivity of the Q linker regions of both NIFA and NIFL occurred when the complex was formed in the presence of MgADP. The N-terminal domain of NIFA adjacent to the Q linker was also protected by NIFL. Experiments with truncated versions of NIFA demonstrate that the central domain of NIFA is sufficient to cause protection of the Q linker of NIFL, although in this case, stable protein complexes are not detectable by cochromatography.

The effects of Cyclosporin-A (CYA) on the Ultrastructure of Gingival Mast Cells (GMC) in Behcet's disease (BD)

1990 ◽  
Vol 48 (3) ◽  
pp. 358-359
Author(s):  
Oktay Arda ◽  
Ulkü Noyan ◽  
Selgçk Yilmaz ◽  
Mustafa Taşyürekli ◽  
İsmail Seçkin ◽  
...  
Keyword(s):  
Unknown Etiology ◽  
Control Group ◽  
Target Cells ◽  
Gingival Hyperplasia ◽  
Cellular Activity ◽  
Direct Relation ◽  
Immune Disease ◽  
Genital Ulceration ◽  
Functional Changes ◽  
The Third

Turkish dermatologist, H. Beheet described the disease as recurrent triad of iritis, oral aphthous lesions and genital ulceration. Auto immune disease is the recent focus on the unknown etiology which is still being discussed. Among the other immunosupressive drugs, CyA included in it's treatment newly. One of the important side effects of this drug is gingival hyperplasia which has a direct relation with the presence of teeth and periodontal tissue. We are interested in the ultrastructure of immunocompetent target cells that were affected by CyA in BD.Three groups arranged in each having 5 patients with BD. Control group was the first and didn’t have CyA treatment. Patients who had CyA, but didn’t show gingival hyperplasia assembled the second group. The ones displaying gingival hyperplasia following CyA therapy formed the third group. GMC of control group and their granules are shown in FIG. 1,2,3. GMC of the second group presented initiation of supplementary cellular activity and possible maturing functional changes with the signs of increased number of mitochondria and accumulation of numerous dense cored granules next to few normal ones, FIG. 4,5,6.

Phospholipid-Protein Interactions in the Formation of Prothrombin Activator

1965 ◽  
Vol 14 (03/04) ◽  
pp. 431-444 ◽  
Author(s):  
E. R Cole ◽  
J. L Koppel ◽  
J. H Olwin
Keyword(s):  
Complex Formation ◽  
Protein Interactions ◽  
Calcium Ions ◽  
Fixed Number ◽  
Factor V ◽  
Clotting Factors ◽  
Number Of Binding Sites ◽  
C Complex ◽  
Autoprothrombin C

SummarySince Ac-globulin (factor V) is involved in the formation of prothrombin activator, its ability to complex with phospholipids was studied. Purified bovine Ac-globulin was complexed to asolectin, there being presumably a fixed number of binding sites on the phospholipid micelle for Ac-globulin. In contrast to the requirement for calcium ions in the formation of complexes between asolectin and autoprothrombin C, calcium ions were not required for complex formation between asolectin and Ac-globulin to occur ; in fact, the presence of calcium prevented complex formation occurring, the degree of inhibition being dependent on the calcium concentration. By treating isolated, pre-formed aso- lectin-Ac-globulin complexes with calcium chloride solutions, Ac-globulin could be recovered in a much higher state of purity and essentially free of asolectin.Complete activators were formed by first preparing the asolectin-calcium- autoprothrombin C complex and then reacting the complex with Ac-globulin. A small amount of this product was very effective as an activator of purified prothrombin without further addition of calcium or any other cofactor. If the autoprothrombin C preparation used to prepare the complex was free of traces of prothrombin, the complete activator was stable for several hours at room temperature. Stable preparations of the complete activator were centrifuged, resulting in the sedimentation of most of the activity. Experimental evidence also indicated that activator activity was highest when autoprothrombin C and Ac-globulin were complexed to the same phospholipid micelle, rather than when the two clotting factors were complexed to separate micelles. These data suggested that the in vivo prothrombin activator may be a sedimentable complex composed of a thromboplastic enzyme, calcium, Ac-globulin and phospholipid.

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