1,720,975 research outputs found
Cell surface control of the multiubiquitination and deubiquitination of high-affinity immunoglobulin E receptors.
No full textMultiubiquitination of proteins is a critical step leading to selective degradation for many polypeptides. Therefore, activation-induced multiubiquitination of cell surface receptors, such as the platelet-derived growth factor (PDGF) receptor and the T cell antigen (TCR) receptor, may correspond to a degradation pathway for ligand-receptor complexes. Here we show that the antigen-induced engagement of high-affinity immunoglobulin E receptors (Fc epsilon RI) results in the immediate multiubiquitination of Fc epsilon RI beta and gamma chains. This ubiquitination is independent of receptor phosphorylation and is restricted to activated receptors. Surprisingly, receptor multiubiquitination is immediately reversible when receptors are disengaged. Therefore, multiubiquitination and deubiquitination of Fc epsilon RI receptors is controlled at the cell surface by receptor engagement and disengagement. The rapidity, specificity and, most importantly, the reversibility of the activation-induced receptor multiubiquitination suggest that this process may turn on/off a cell surface receptor signaling function thus far unsuspected
The high-affinity Iimmunoglobulin-E receptor- Structure, function and prospects for therapy
No full textCOORDINATE SYNTHESIS AND DEGRADATION OF THE ALPHA-SUBUNIT, BETA-SUBUNIT AND GAMMA-SUBUNIT OF THE RECEPTOR FOR IMMUNOGLOBULIN-E
No full textIgE receptor (FcepsilonRI) and signal transduction.
No full textThis review suggests a model in which both beta- and gamma-chains synergize in the initiation of Fc epsilon RI signal transduction function. Receptor aggregation by antigens induces activation of lyn, which is already bound to the Fc epsilon RI beta-chain under resting conditions. Whilst activated, lyn would phosphorylate the tyrosine residues in the Fc epsilon RI gamma-chain. This phosphorylation would be responsible for the recruitment of syk (probably via its SH2 domains) as well as other signalling molecules. Syk kinase would then be activated by the engagement of its SH2 domains and/or its phosphorylation. Syk could then interact with and activate (through phosphorylation) downstream effector molecules
Studies with a monoclonal antibody to the beta subunit of the receptor with high affinity for immunoglobulin E
No full textThe receptor with high affinity for IgE consists of a tetrameric complex of polypeptides, one of which (alpha), contains the binding site for IgE. The function of the other chains--a single beta and two disulfide-linked gamma chains--is unknown. We report the cloning of a murine hybridoma that secretes an IgG1 antibody which specifically reacts with the beta subunit. Studies with this monoclonal antibody show that the subunit stoichiometry of the receptor is unaffected by the presence or absence of bound IgE. We also found that under certain conditions where the alpha beta gamma 2 complex dissociates, beta remains attached to the dimer of gamma chains, indicating that these chains contact each other in the native receptor. In rat basophilic leukemia cells--a neoplastic line of mucosal-type mast cells--all of the beta subunits expressed by the cells appeared to be associated with the high affinity receptor. However, in at least one cell line which has no high affinity receptors--a putative rat lymphoma line--beta or beta-like polypeptides were also expressed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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