Receptors binary complexes

Thus, the transfer of first messenger to second messenger is accomplished by means of a molecular cascade neurotransmitter to neurotransmitter receptor (Fig. 2—25) neurotransmitter receptor to G protein (Fig. 2—26) binary complex of two receptors to enzyme (Fig. 2—27) and enzyme to second-messenger molecule (Fig. 2-28). 

We anticipate further development of lanthanide binary complexes as receptors for aromatic ions, with the ultimate goal of generating highly specific devices capable of sensitive detection in matrices such as environmental samples or biological fluids. The possibility of using several lanthanide sensors... 

Stoddard, B.L. and Koshland Jr., D.E. (1992). Prediction of the structure of a receptor protein complex using binary docking method. Nature 358,774 778. 

Binary toxins are unique concerning their structure because they are comprised of two individual, nonlinked proteins represented by an enzyme component and a binding/translocation component. The two components are secreted by the bacterium and assemble upon the surface of targeted eukaryotic cells to form an active toxin complex. For this to occur, both protein components of binary toxins act in a precisely concerted manner. The binding component first engages the cell-surface receptor and then mediates translocation of enzyme compo-nent(s) from the outside of a cell, through acidified endosomes, and into the host cell cytosol where it modifies the substrate (for review see Barth ). 

Fig. 3. Binary delivery mechanism. Bispecific antibodies can be used to deliver the complementary parts of an effector molecule to two distinct target sites on the same cell. In the example shown one acid-triggered bispecific antibody carries the catalytic domain (C) of DT to a selected receptor whereas the second carries its transmembrane domain (T) to a different receptor site. Cooperation between these functional units should occur when both complexes enter the same endosome and their bound toxin domains are released by the low pH conditions. Greatly improved specificity results from targeting two distinct sites on the cell and unwanted side effects are reduced by using attenuated effector moieties whose activity is restored intracellularly.

Seth A, Stem LJ, OttenhofFTH, Engel I, Owen MJ, Lamb JR, Klausner RD, Wiley DC Binary and ternary complexes between T-cell receptor, class II MHC and superantigen in vitro. Nature 1994 369 324-327. 

The equilibria (1-5) described above now need to be supplemented, first to take account of the receptor itself, and second to allow for the receptor complexes with the various components of binary and ternary aggregates shown in Scheme 1-23 altogether eight molecular species are now involved. Scheme 1-25 shows the corresponding network of 8 nodes and 28 possible equilibria, each of the nodes having 7 connections. As in Scheme 1-22, green, red, and blue lines represent the possible binary equilibria, whilst black lines denote potential ternary and quaternary equilibria. 

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