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Protein A

About: Protein A is a research topic. Over the lifetime, 2475 publications have been published within this topic receiving 99609 citations.


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TL;DR: Bacterial adsorbent not only had a distinct advantage in speed of antigen isolation, but analyses by polyacrylamide gel electrophoresis in SDS also revealed consistently higher antigen recoveries, lower levels of background radioactivity, and an absence of other cell components which may nonspecifically bind to and complicate analyses using conventional immune precipitates.
Abstract: The Cowan I strain of the bacterium Staphylococcus aureus has been used as an adsorbent for antibodies complexed with radiolabeled antigens from cell lysates. This application is advanced as a superior alternative to other methods of immune precipitation for the isolation of antigens. It exploits the high adsorption capacity for IgG molecules by protein A molecules on the cell walls of certain strains of staphylococci, along with the advantageous sedimentation properties of the bacteria. The interaction of immune complexes with the adsorbent was defined initially using a model system of bovine serum albumin with a high excess of rabbit anti-bovine serum albumin antibodies (IgG). The uptake of immune complexes under these conditions was extremely rapid, occurring within seconds, whereas maximum binding of free IgG was much slower. In addition, once bound the complexed antigen could not be displaced from the adsorbent either by large amounts of normal IgG or by extra free antibody. Antigen could be eluted almost completely from the inert adsorbent for analytic or preparative purposes with a variety of solvent systems, such as the detergent SDS in combination with urea and high temperature, and neutral salts with strong lyotropic salting in properties. The efficacy of the protein A-antibody adsorption technique was tested in direct comparisons with a conventional double antibody precipitation method for the isolation of mouse lymphocyte IgM. The bacterial adsorbent not only had a distinct advantage in speed of antigen isolation, but analyses by polyacrylamide gel electrophoresis in SDS also revealed consistently higher antigen recoveries, lower levels of background radioactivity, and an absence of other cell components which may nonspecifically bind to and complicate analyses using conventional immune precipitates.

2,764 citations

Journal Article
TL;DR: Protein A was isolated from S. aureus and shown to precipitate about 45% of a pooled normal human γG preparation, but this reaction is not a true antigen-antibody reaction.
Abstract: Protein A was isolated from S. aureus and shown to precipitate about 45% of a pooled normal human γG preparation. In addition it was demonstrated that protein A reacts with myeloma γG-globulin, H chains from both normal and myeloma γG-globulins and the Fc fragment of normal γG-globulin. Thus, the reaction is not a true antigen-antibody reaction.

1,033 citations

Journal ArticleDOI
TL;DR: Protein A has proven useful for the study of antigens and receptors on the surface of intact cells, and for the detection of antibody-secreting cells, so the use of protein A is now the method of choice for many preparative and analytical purposes in immunology.

936 citations

Journal ArticleDOI
TL;DR: The results suggest that IgG1 might be the favoured IgG subclass for therapeutic applications in complement-dependent hemolysis and in antibody-dependent cell-mediated cytotoxicity using both human effector and human target cells.
Abstract: Cell lines have been established that secrete a matched set of human chimeric IgM, IgG1, IgG2, IgG3, IgG4, IgE, and IgA2 antibodies that are directed against the hapten 4-hydroxy-3-nitrophenacetyl. These chimeric antibodies secreted from mouse plasmacytoma cells behave exactly like their authentic human counterparts in SDS-PAGE analysis, binding to protein A and in a wide range of serological assays. The antibodies have been compared in their ability to bind human C1q as well as in their efficacy in mediating lysis of human erythrocytes in the presence of human complement. A major conclusion to emerge is that whereas IgG3 bound C1q better than did IgG1, the chimeric IgG1 was much more effective than all the other IgG subclasses in complement-dependent hemolysis. The IgG1 antibody was also the most effective in mediating antibody-dependent cell-mediated cytotoxicity using both human effector and human target cells. These results suggest that IgG1 might be the favoured IgG subclass for therapeutic applications.

750 citations

Journal ArticleDOI
TL;DR: A rapid and very sensitive method for detecting proteins as antigens after their separation in polyacrylamide/agarose composite gels, with or without sodium dodecyl sulfate.
Abstract: We describe a rapid and very sensitive method for detecting proteins as antigens after their separation in polyacrylamide/agarose composite gels, with or without sodium dodecyl sulfate. The polyacrylamide matrix is crosslinked with a reagent that can be cleaved with periodate or alkali to facilitate transfer of the protein bands to diazobenzyloxymethyl-paper, where they are coupled covalently. Specific proteins are detected by autoradiography after sequential incubation with unfractionated, unlabeled specific antiserum and 125I-labeled protein A from Staphylococcus aureus. Antibody and protein A can be removed with urea and 2-mercaptoethanol, and the same paper can be probed again with a different antiserum. An antiserum specific for the simian virus 40 virion proteins VP3 and VP2 has been prepared; it does not crossreact with VP1, as demonstrated by this method. An antiserum raised in rabbits against simian virus 40-transformed rabbit kidney cells is shown to be directed primarily against a periodate-sensitive moiety present in tumor (T) antigen from infected or transformed cells, whereas an antiserum raised in rabbits against large T antigen purified from lytically infected monkey kidney cells by electrophoresis in the presence of sodium dodecyl sulfate [Lane, D.P. & Robbins, A.K. (1978) Virology 87, 182-193] is directed primarily against determinants that are not sensitive to periodate.

734 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20237
20227
202135
202031
201938
201839