Antibodies to
Cell Surface Receptors

Cell surface receptors are glycoproteins that are embedded or otherwise attached to the cell's plasma membrane and have a binding site for specific ligands (cytokines, hormones, grothfactors, neurotransmitters, adhesion molecules, etc) exposed to the extracellular environment. Ligand binding to a cell surface receptor generally leads to a biological signal that is propagated from the receptor towards the cell interior, resulting in a cellular response such as prolifereation, differentiation, apoptosis, degranulation, etc. Cell surface receptors transduce ligand signals by a variety of mechanisms such as receptor clustering, activation of a hidden enzymatic activity, opening of ion channels, etc. Cell surface receptors pose specific challenges to antibody development as most are not available in quantities sufficient for immunization unless generated artificially by recombinant gene expression. Many receptors such as G-protein coupled receptors traverse the membrane several times and cannot be expressed as recombinant soluble fragments. The binding geometry between receptor and antibody is of outmost important in determining the biological effect of the antibody, i.e. whether it may be blocking, neutralizing, activating, or not interfering with receptor function. Glycosylation of a cell surface receptor can further compound antibody design.

Monoclonal antibodies are the tools of choice to probe for cell surface receptor expression, distribution, and function. Typically, animals are immunized with whole cell, or cell membranes, that express or a engineered to overexpress the receptor of interest. Spleens from immunized animals are fused with myeloma cells, and resulting hybridomas are screened for those secreting the desired antibody by cell-based ELISA, flow cytometry, or an applicable functional assay. When the ligand binding domain of a receptor can be expressed as recombinant soluble protein, standard immunization protocols can be followed. Some types of receptors require additional manipulation for most efficient expression and antigenicity.

Antibody Solutions
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