Immunoglobulin receptor ligands

Surface immunoglobulin receptor of human B-cell lymphoma Tumor suppressor protein p53 mAb 5.5 against the ligand-binding site ot the nicotinic acetylcholine receptor Bovine pancreatic RNase fragment concanavalin A... 

Proteins secreted by solid tissues that act in plasma - classical plasma proteins for liver and gut e.g. albumin Immunoglobulins - some 10 million antibodies Long distance receptor ligands - classical peptide and protein hormones... 

Fig. 1. Interaction of cells with the ECM is mediated by ligand binding to cell surface receptors, such as selectins, immunoglobulins, and integrins. Receptor-ligand binding allows cells to respond to changes in their extracellular environment. The general structure of these three types of receptors is illustrated here.

The receptor-mediated form of endocytic uptake has been identified for a wide variety of physiological ligands, such as metabolites, hormones, immunoglobulins, and pathogens (e.g., virus and bacterial and plant toxins). Several endosomotropic receptors identified in cells are listed in Table 2. 

Etanercept is a recombinant fusion protein produced in Chinese hamster ovary cells. It consists of the intracellular ligand-binding portion of the human p75 TNF receptor linked to the Fc portion of human immunoglobulin (Ig) Gi. Two p75 molecules are attached to each Fc molecule. Etanercept binds to soluble TNF-a and TNF-(3 and forms inactive complexes, effectively lowering circulating levels of these cytokines. It is administered subcutaneously, generally twice weekly. 

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