• Now, immuno globulin are going to be the class of proteins that include antibodies and B cell receptors. (pearson.com)
  • So the B cell receptor is has the same structure is the antibodies produced by those B cells and it's gonna be made up of what were called heavy chains and light chains, two of each, actually too heavy chains to light chains. (pearson.com)
  • And as I've said before, you know, the only real difference between the B cell receptor and antibodies it produces is that the B cell receptor is gonna have a trans membrane domain. (pearson.com)
  • Herein we used a single bicistronic lentiviral vector to develop a new combination immunotherapy that consists of human anti-carbonic anhydrase IX (CAIX)-targeted chimeric antigen receptor (CAR) T cells engineered to secrete human anti-programmed death ligand 1 (PD-L1) antibodies at the tumor site. (oncotarget.com)
  • Latex bound anti-sTfR antibodies react with the antigen in the sample to form an antigen/antibody complex. (cdc.gov)
  • cells are activated by interaction with antigens and obtain T indicated that the cell lines representing a defined cell help, they mature into terminally differentiated plasma stage generally presented a high similarity in over- cells secreting large amounts of antibodies [10 -12]. (lu.se)
  • Monoclonal antibodies attach to specific proteins or antigens. (who.int)
  • Chimeric antigen receptors (CARs) are synthetic proteins expressed on the surface of T cells. (medscape.com)
  • These fusion proteins are intended to work in similar fashion as the MHC Tetramers used for identification of antigen-specific T-cells, and may also have other applications in studies of activation of anti-CD19 CAR bearing cells. (escholarship.org)
  • Both of these tailspike proteins also contain right-handed parallel beta-helices and share similar O-antigen binding and cleavage to P22TSP. (wikipedia.org)
  • BMPR family of proteins is a valuable tool for studying ligand-receptor interactions, downstream signaling events, and determining therapeutic targets. (news-medical.net)
  • The ALK gene provides instructions for making a protein called ALK receptor tyrosine kinase, which is part of a family of proteins called receptor tyrosine kinases (RTKs). (medlineplus.gov)
  • We have different B cells, each with a specific type of B cell receptor that is meant for a specific type pathogen. (pearson.com)
  • On their surface, these special white blood cells carry a receptor that recognizes antigens . (news-medical.net)
  • They carry a special receptor called the T-cell receptor on their surface that recognizes antigens - small protein fragments of bacteria, viruses and infected or cancerous body cells - which are presented by specialized immune complexes. (news-medical.net)
  • Chimeric antigen receptor-modified T cells with specificity for CD19 have shown promise in the treatment of chronic lymphocytic leukemia (CLL). (nih.gov)
  • It remains to be established whether chimeric antigen receptor T cells have clinical activity in acute lymphoblastic leukemia (ALL). (nih.gov)
  • Two children with relapsed and refractory pre-B-cell ALL received infusions of T cells transduced with anti-CD19 antibody and a T-cell signaling molecule (CTL019 chimeric antigen receptor T cells), at a dose of 1.4×10(6) to 1.2×10(7) CTL019 cells per kilogram of body weight. (nih.gov)
  • In addition, the chimeric antigen receptor T cells were observed in the cerebrospinal fluid (CSF), where they persisted at high levels for at least 6 months. (nih.gov)
  • cytokine blockade with etanercept and tocilizumab was effective in reversing the syndrome and did not prevent expansion of chimeric antigen receptor T cells or reduce antileukemic efficacy. (nih.gov)
  • Chimeric antigen receptor-modified T cells are capable of killing even aggressive, treatment-refractory acute leukemia cells in vivo. (nih.gov)
  • Once infused, the cells continue to expand in number and bind to cancer cells via the engineered receptor, resulting in immunologic cancer cell death. (medscape.com)
  • We designed a lentiviral vector expressing a chimeric antigen receptor with specificity for the B-cell antigen CD19, coupled with CD137 (a costimulatory receptor in T cells [4-1BB]) and CD3-zeta (a signal-transduction component of the T-cell antigen receptor) signaling domains. (nih.gov)
  • A low dose (approximately 1.5×10(5) cells per kilogram of body weight) of autologous chimeric antigen receptor-modified T cells reinfused into a patient with refractory chronic lymphocytic leukemia (CLL) expanded to a level that was more than 1000 times as high as the initial engraftment level in vivo, with delayed development of the tumor lysis syndrome and with complete remission. (nih.gov)
  • Apart from the tumor lysis syndrome, the only other grade 3/4 toxic effect related to chimeric antigen receptor T cells was lymphopenia. (nih.gov)
  • Engineered cells persisted at high levels for 6 months in the blood and bone marrow and continued to express the chimeric antigen receptor. (nih.gov)
  • Adoptive cell therapy (ACT) with chimeric antigen receptor T (CAR-T) cells can restore the activity of exhausted T cell through reprogramming and is widely used in the treatment of relapsed/refractory (r/r) hematological malignancies. (hindawi.com)
  • Here, we demonstrate that NK cells (haNKs) engineered to express a PD-L1 chimeric antigen receptor (CAR) haNKs killed a panel of human and murine head and neck cancer cells at low effector-to-target ratios in a PD-L1-dependent fashion. (elifesciences.org)
  • T cell-based immunotherapy, such as immune checkpoint blockade or adoptive T cell transfer, is limited by the ability of T cells to detect major histocompatibility complex (MHC)-presented antigen by tumor cells. (elifesciences.org)
  • Natural killer (NK) cell-based immunotherapy may overcome genetic mechanisms of resistance to T cell-based immunotherapy through antigen- and MHC-independent recognition of malignant cells. (elifesciences.org)
  • NK cells express germ-line receptors that are either stimulatory or inhibitory, and the summation of these signals determines activation status ( Caligiuri, 2008 ). (elifesciences.org)
  • Here, we describe the pre-clinical in vitro and in vivo study of irradiated haNK cells engineered to express a second-generation chimeric antigen receptor (CAR) targeting programmed death-ligand 1 (PD-L1). (elifesciences.org)
  • AR-regulated human kallikrein-related peptidase 2 (free hK2) is a prostate tissue-specific antigen produced in prostate cancer and androgen-stimulated breast cancer cells. (lu.se)
  • The T-cell receptor (TCR) is a highly polymorphic surface receptor that allows T-cells to recognize antigenic peptides presented on the major histocompatibility complex (MHC). (eur.nl)
  • One of the major questions regarding the roles of T-cells is whether expansion and activation of T-cells observed in the diseases pathogenesis is antigen driven. (eur.nl)
  • These data provide evidence for an antigen driven expansion of CD4+/CD8+ T-cells in SSc. (eur.nl)
  • One example is adoptive cell therapy with T cells that were genetically modified with gamma-retroviral and lentiviral (LV) delivery vectors to express a CD19-specific chimeric antigen receptor (CAR) for cancer treatment. (uni-wuerzburg.de)
  • Chimeric Antigen Receptors (CARs) consist of the antigen-recognition portion of a monoclonal antibody fused to an intracellular signaling domain capable of activating T-cells. (escholarship.org)
  • CARs displayed on the surface of transduced cells perform non-MHC-restricted antigen recognition and activating intracellular signaling pathways for induction of target cytolysis, cytokine secretion and proliferation. (escholarship.org)
  • Navai SA, Ahmed N. Broad Spectrum Chimeric Antigen Receptor T Cells to Target the Tumor Profile. (standuptocancer.org)
  • We now evaluate whether we can enhance wild-type (WT) or p50-IMC tumor localization and/or the phagocytosis of PSMA+ prostate cancer cells by expressing a prostate-specific membrane antigen (PSMA)-specific chimeric antigen receptor (CAR) on IMC, or by combining IMC with PSMA antibody (Ab), which binds to the surface of myeloid cells via their Fc receptors. (bmj.com)
  • Uptake of carcinoembryonic antigen (CEA) by isolated rat alveolar cells was time, temperature, and concentration dependent (Kuptake = 2.4 x 10(-7) M). Pretreatment of the alveolar cells with colchicine inhibited internalization of CEA. (duke.edu)
  • Uptake of 125I-labeled CEA by alveolar cells required divalent cations and was inhibited by cold CEA and nonspecific cross-reacting antigen (NCA). (duke.edu)
  • Recombinant human angiotensin-converting enzyme 2 (ACE2) extracellular domain (18-615) was expressed in HEK293 cells using a C-terminal sheep Fc-tag and purified to SARS-CoV-2 receptor binding domain (RBD) of the spike protein binds to the host cell ACE2 receptor to facilitate viral entry into the cell. (thenativeantigencompany.com)
  • T-cell receptors composed of CD3-associated alpha and beta polypeptide chains and expressed primarily in CD4+ or CD8+ T-cells. (uams.edu)
  • To this end we have used chimeric antigen receptors (CARs), a very promising approach recently used in several clinical trials to redirect primary human T cells against different tumours. (uninsubria.it)
  • Results: In this proof-of-concept study, retrovirus-transduced human T cells expressing anti-HCV/E2 CARs were endowed with specific antigen recognition accompanied by degranulation and secretion of proinflammatory and antiviral cytokines, such as interferon gamma, interleukin 2 and tumour necrosis factor a. (uninsubria.it)
  • One way to achieve this is to genetically modify immune cells, mainly T cells and recently also natural killer (NK) cells, to express chimeric antigen receptors (CARs). (nature.com)
  • CAR-expression on T or NK cells allows them to specifically target cancer cells via recognition of tumor associated antigens. (nature.com)
  • The addition of separate adapter molecules (AMs) specific for tumor antigens and CAR-immune cells targeting these AMs allows a more precise and temporally limited therapy. (nature.com)
  • NK cells contribute to cancer immune surveillance not only by their direct natural cytotoxicity which is triggered rapidly upon stimulation through germline-encoded cell surface receptors, but also by modulating T-cell mediated antitumor immune responses through maintaining the quality of dendritic cells and enhancing the presentation of tumor antigens. (frontiersin.org)
  • Furthermore, similar to T cells, specific recognition and elimination of cancer cells by NK cells can be markedly enhanced through expression of chimeric antigen receptors (CARs), which provides an opportunity to generate NK-cell therapeutics of defined specificity for cancer immunotherapy. (frontiersin.org)
  • Here, we discuss effects of the GB tumor microenvironment on NK-cell functionality, summarize early treatment attempts with ex vivo activated NK cells, and describe relevant CAR target antigens validated with CAR-T cells. (frontiersin.org)
  • The clonal selection theory, developed by MacFarland Burnet in the late 1950s, says that antigens, not cells, control the immune response. (pharmacygyan.com)
  • To create a repertoire of antigen-specific TCRs, alternative forms of genes present in somatic cells are rearranged in a process, called somatic cell recombination, by using RAG-1 and RAG-2 recombinase activating enzymes showing in above figure. (pharmacygyan.com)
  • The NKp44 activating receptor is the only natural cytotoxicity receptor that is expressed exclusively by primate NK cells, yet its cellular ligands remain largely unknown. (bgu.ac.il)
  • Here we show that chimeric antigen receptor (CAR) T cells could successfully target an isoform of alkaline phosphatase, ALPL-1, which is highly and specifically expressed in primary and metastatic OS. (opinvisindi.is)
  • Chimeric antigen receptor (CAR) T cells are engineered T cells that are transduced to express an artificially modified receptor that directly binds to target antigens on tumor cells. (apbmt.org)
  • recognition of the target tumor-associated antigen, followed by CAR T cell activation, expansion, and immune-killing of the cancer cells, as well as sufficient persistence to provide immune surveillance for tumor control. (apbmt.org)
  • Neoadjuvant anti-OX40 (MEDI6469) therapy in patients with head and neck squamous cell carcinoma activates and expands antigen-specific tumor-infiltrating T cells. (bepress.com)
  • Analyses of CD8+ TIL show increases in tumor-antigen reactive, proliferating CD103+ CD39+ cells in 25% of patients with evaluable tumor tissue (N = 4/16), all of whom remain disease-free. (bepress.com)
  • Immunotherapies are changing the treatment paradigm of MM and have improved the overall response and survival of patients with relapsed/refractory (RR) MM. B cell maturation antigen (BCMA), selectively expressed in normal and malignant plasma cells , has been targeted by several immunotherapeutic modalities. (bvsalud.org)
  • Chimeric antigen receptor ( CAR ) T cells , the breakthrough in cancer immunotherapy , have revolutionized the treatment of B cell malignancies and remarkably improved the prognosis of RRMM. (bvsalud.org)
  • Polymorphisms in the capital Killer Cells Immunoglobulin-like Receptor (kirs). (hla-dr.com)
  • BCR microclusters on the surface of ABC cells resemble those generated following antigen engagement of normal B cells. (arizona.edu)
  • Hence, a diverse set of self-antigens is responsible for maintaining the malignant survival of ABC DLBCL cells. (arizona.edu)
  • Although the specific function of ALK receptor tyrosine kinase is unknown, it is thought to act early in development to help regulate the proliferation of nerve cells. (medlineplus.gov)
  • Constitutive activation of ALK receptor tyrosine kinase may increase the proliferation of immature nerve cells, leading to neuroblastoma. (medlineplus.gov)
  • HLA, human leukocyte antigen. (cdc.gov)
  • Class II Human Leukocyte Antigen (HLA) play an important role in host protection from foreign. (hla-dr.com)
  • Background: Monocytic human leukocyte antigen DR (mHLA-DR) expression levels have been reported to be a marker of immunosuppression and predictors of sepsis and death. (hla-dr.com)
  • And I'm gonna jump out of the way here and you can see that we have a T cell receptor right here T cell receptor, and it has its Alfa chain and its beta chain, and it's kind of like just one of these arms from the B cell receptor from an antibody. (pearson.com)
  • It is proposed that rapid in vivo modulation of lymphocyte Fcγ-receptors occurs following oral antigen (cows' milk) challenge probably mediated by soluble food antigen-antibody complexes. (karger.com)
  • We report intracellular accumulation of a secreted antigen-targeted antibody (SATA) that can be used to characterize disease, guide therapy, and monitor response. (lu.se)
  • Human IgG antibody Laboratories manufactures the sars antigen postive reagents distributed by Genprice. (toll-likereceptors.com)
  • Classical " CARs consist of an extracellular binding domain mostly derived from a monoclonal antibody fragment (single-chain variable fragment-scFv), which is linked to intracellular binding domains of the T-cell receptor complex. (nature.com)
  • A CD19/Fc fusion protein for detection of anti-CD19 chimeric antigen receptors. (escholarship.org)
  • Clinical trials are in progress assessing the use of mature T-lymphocytes transduced with CARs targeting CD19 antigen to treat B-lineage malignancies. (escholarship.org)
  • Many surface receptors relay signals into the interior of the cell by changing their spatial structure after ligand binding. (news-medical.net)
  • The most active T cell endogenous inhibitory pathway is the immunoglobulin superfamily such as CD28/cytotoxic T lymphocyte antigen-4 (CTLA-4): B7-1/B7-2 receptor/ligand grouping, which plays a central role in coordinating immune responses [ 7 , 8 ]. (hindawi.com)
  • The cryo-EM structure of the fully assembled T-cell receptor (TCR) complex with a tumor-associated peptide/MHC ligand provides important insights into the biology of TCR signaling. (nanotech-now.com)
  • Such receptors exhibit unique ligand-binding specificities and mediate distinct signaling cascades, even though they could cross-interact with other TGF-β family ligands. (news-medical.net)
  • Diverse repertoires of hypervariable immunoglobulin receptors (TCR and BCR) recognize antigens in the adaptive immune system. (elifesciences.org)
  • Unlike immunoglobulins, the alpha-beta T-cell receptors recognize antigens only when presented in association with major histocompatibility (MHC) molecules. (uams.edu)
  • However, how this signaling pathway is activated has remained a mystery until now - despite the fact that the T-cell receptor is one of the most extensively studied receptor protein complexes. (news-medical.net)
  • There is evidence that this protein can serve as an alternative entry receptor for SARS-CoV-2. (thenativeantigencompany.com)
  • Mammalian expressed recombinant MXRA8 protein, the cell surface receptor for alphaviruses. (thenativeantigencompany.com)
  • They suggest that the endorhamnosidase activity of the free tailspike molecule serves to modify O-antigen, compromising the LPS structure and thereby preventing the binding of a phage P22-attached tailspike protein. (wikipedia.org)
  • The Bone Morphogenetic Protein Receptor ( BMPR ) family includes transmembrane receptors that play vital roles in tissue development and cellular signaling. (news-medical.net)
  • analyzed the impact of RN1 (a natural product extracted from Panax notoginseng ) on bone morphogenetic protein receptors (BMPR1A and BMPR2). (news-medical.net)
  • Mutations in the ALK gene change single protein building blocks (amino acids) in ALK receptor tyrosine kinase. (medlineplus.gov)
  • They function as receptors for the complex of lipopolysaccharide (LPS) and LPS-binding protein. (bvsalud.org)
  • These insights into the nature of TCR assembly and the unusual cell membrane architecture reveal the basis of antigen recognition and receptor signaling. (nanotech-now.com)
  • The modified glycoproteins inhibited endocytosis by the alveolar macrophages, thus excluding nonreducing terminal carbohydrate residues as the recognition site of the receptor. (duke.edu)
  • Furthermore, the so-called adapter CARs have been developed by splitting antigen recognition and CAR-immune cell activation. (nature.com)
  • CDR2s interact with the class II molecules but are not involved in antigen recognition. (pharmacygyan.com)
  • For the structural analysis, the researchers chose a T-cell receptor used in immunotherapy to treat melanoma and which had been optimized for this purpose in several steps in such a way that it binds its antigen as tightly as possible. (news-medical.net)
  • 3) The T cell's CD28 binds with a B7 molecule on the APC in the last stage of the activation cycle (antigen-presenting cell). (pharmacygyan.com)
  • chain repertoires, by establishing a near-complete list of unique receptor chain sequences, or 'clonotypes', present in a sample. (elifesciences.org)
  • The method for measurement of soluble transferrin receptor (sTfR) is immuno-turbidimetry using Roche kits on the Hitachi 912 clinical analyzer. (cdc.gov)
  • and 3) task performance in aged rats only (soluble fibroblast growth factor receptor IIIb, osteoregulin, and osteocalcin). (cdc.gov)
  • Type I receptors consist of BMPR1B (ALK6) and BMPR1A (also called ALK3), while type II receptors comprise BMPR2 and ActRII (Activin receptor type II) subtypes. (news-medical.net)
  • The co-receptor CD8 is known to approach the T-cell receptor after antigen binding and to stimulate the transfer of phosphate groups to its intracellular part. (news-medical.net)
  • These receptors have both extracellular and intracellular components. (medscape.com)
  • This phenomenon was transient and apparently confined to the lymphocyte Fcγ-receptor +ve subpopulation. (karger.com)
  • Lastly, using "Grouping of Lymphocyte Interactions by Paratope Hotspots" (GLIPH2), we identify clusters of TCRβ sequences with homologous sequences that potentially recognize the same antigens and contain TCRβs that are persist in SSc patients. (eur.nl)
  • T cell activation, for example, needs three steps: (1) The lymphocyte T cell receptor (TCR) interacts with the antigen-loaded class II molecule in the first phase. (pharmacygyan.com)
  • The subsequent images collected at the cryo-electron microscope delivered groundbreaking insights into how the T-cell receptor works, as Tampé summarises: 'On the basis of our structural analysis, we were able to show how the T-cell receptor assembles and recognizes antigens and hypothesize how signal transduction is triggered after antigen binding. (news-medical.net)
  • Receptor tyrosine kinases transmit signals from the cell surface into the cell through a process called signal transduction. (medlineplus.gov)
  • The development of immunoglobulin receptor repertoire sequencing methods makes it possible to perform repertoire-wide disease association studies of antigen receptor sequences. (elifesciences.org)
  • Statistical comparison of all inhibitory and activating killer cell immunoglobulin receptors (KIRs) between controls, survivors, and persons who died of Ebola virus disease in Guinea, 2015-2017. (cdc.gov)
  • We applied a genomic DNA-based approach to concurrently study the immunoglobulin-heavy (IGH) and T cell receptor (TCR) β and δ chain loci of 95 individuals. (ucl.ac.uk)
  • Molecule composed of the non-covalent association of the T-cell antigen receptor (RECEPTORS, ANTIGEN, T-CELL) with the CD3 complex (CD3 COMPLEX). (ouhsc.edu)
  • The molecule consists of up to seven chains: either the alpha/beta or gamma/delta chains of the T-cell receptor, and four or five chains in the CD3 complex. (ouhsc.edu)
  • Failed T cell-based immunotherapies in the presence of genomic alterations in antigen presentations pathways may be overcome by NK cell-based immunotherapy. (elifesciences.org)
  • After binding of a suitable antigen to the receptor, a signaling pathway is triggered inside the T cell that 'arms' the cell for the respective task. (news-medical.net)
  • It is anchored within the viral coat and recognizes the O-antigen portion of the lipopolysaccharide (LPS) on the outer-membrane of Gram-negative bacteria. (wikipedia.org)
  • P22TSP recognizes the O-antigen polysaccharide of LPS serotypes A, B, or D1. (wikipedia.org)
  • In this study, we show that the NKp44 receptor recognizes PCNA. (bgu.ac.il)
  • BCMA-targeting chimeric antigen receptor T-cell therapy for multiple myeloma. (bvsalud.org)
  • Recently, chimeric antigen receptor (CAR) T cell therapy has transformed the treatment armamentarium of relapsed/refractory B lymphoid malignancies. (apbmt.org)
  • Dennoch bestätigen funktionelle Assays eine höhere Avidität von Treg TCRs im Vergleich zu Nicht-Tregs TCRs gegenüber dem endogenen Selbst-Antigen MOG35-55. (tu-berlin.de)
  • Simple recombination in the α-chain can result in approximately 4.9 × 103 antigen-specific TCRs. (pharmacygyan.com)
  • With the help of cryo-electron microscopy, biochemists and structural biologists from Goethe University Frankfurt, in collaboration the University of Oxford and the Max Planck Institute of Biophysics, were able to visualize the whole T-cell receptor complex with bound antigen at atomic resolution for the first time. (news-medical.net)
  • Researchers led by Lukas Sušac, Christoph Thomas, and Robert Tampé from the Institute of Biochemistry at Goethe University Frankfurt, in collaboration with Simon Davis from the University of Oxford and Gerhard Hummer from the Max Planck Institute of Biophysics, have now succeeded for the first time in visualizing the structure of a membrane-bound T-cell receptor complex with bound antigen. (news-medical.net)
  • Once they had successfully achieved this, the researchers used a trick to fish those receptors out of the preparation that had survived the process and were still functional: due to the strong interaction between the receptor complex and the antigen, they were able to 'fish' one of the most medically important immune receptor complexes. (news-medical.net)
  • Receptor-CD3 Complex, Antigen, T-Cell" is a descriptor in the National Library of Medicine's controlled vocabulary thesaurus, MeSH (Medical Subject Headings) . (ouhsc.edu)
  • This graph shows the total number of publications written about "Receptor-CD3 Complex, Antigen, T-Cell" by people in this website by year, and whether "Receptor-CD3 Complex, Antigen, T-Cell" was a major or minor topic of these publications. (ouhsc.edu)
  • Below are the most recent publications written about "Receptor-CD3 Complex, Antigen, T-Cell" by people in Profiles. (ouhsc.edu)
  • The M-type phospholipase A2 receptor (PLA2R) in the glomerular podocyte has been identified as the major target antigen in deposited immune-complexes. (msdmanuals.com)
  • Also, CD4 antigen, IL-4 and IL-10 mRNA decreased in young 3 week HRLF rats, but not in aged HRLF rats. (cdc.gov)
  • Binding of a tumor antigen via the scFv activates the T cell in a major histocompatibility-independent manner which leads to a cytotoxic response [ 3 ]. (nature.com)
  • The T cell receptor is a heterodimer with two chains, one variable (V) and the other constant (C). The structure of an α/β TCR is shown in the Figure below. (pharmacygyan.com)
  • The subsequent recovery of these receptors in vivo and in vitro may be due to the binding of 'fluid-phase' Fcγ-receptors found in normal human serum. (karger.com)
  • In addition, it's an important stimulus for employing the T-cell receptor in a therapeutic context for treating infections, cancer, and autoimmune diseases. (nanotech-now.com)
  • Given the BMPR family's considerable involvement in several diseases, targeting these receptors presents a hopeful avenue for therapeutic interventions. (news-medical.net)
  • every B and T cell is going to have a single type of antigen receptor, and that's going to be specific. (pearson.com)
  • It's not just specific for B cell receptors. (pearson.com)
  • So here, looking at RB cell receptor, these little pieces that you see on either side, those are the light chains, and these bigger pieces that you see here and here will draw a red line through them just to be super crystal clear. (pearson.com)
  • or both chains is convergent selection in response to a common antigen. (elifesciences.org)
  • Complementarity determining regions (CDRs), which are hypervariable in the Vα/β-chains have actual contact with antigens. (pharmacygyan.com)