Receptor Material

Between R and R there are only small differences in energy. This can be seen by single amino acid mutations leading to constitutive receptor activity [12-14]. Conformational selection and conformational induction, however, are not necessarily in contradiction. Both can be seen as two parts of one mechanism in which the active conformation of a receptor is induced during the binding process, whereas the ligand preferably binds to the active conformation [15]. 

Usually, G-protein-coupled receptors and their ligands are first identified from primary tissue. However, it is difficult and also ethically questionable to get large enough amounts of primary tissue samples to closely investigate them. Furthermore, the stability of those samples and the accessibility of the embedded receptors can be a problem. There are different ways to circumvent those difficulties. Probably the easiest way is the isolation and cultivation of cancer cell lines that endogenously express the receptors that are of interest. This has been done with the SK-N-MC [19] cell line and the SMS-KAN cell line [20], which express the Nl Y-Y, and the NPY-Y2 receptor, respectively. Another commonly used method is the cloning of the recep- 

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Lack of In Vitro Model System. Whereas there are a variety of in vitro receptor models fora- and 6-adrenoreceptors there has been less progress on well accepted models for dopamine receptors. Tissue culture may well be used increasingly in the future as a source of receptor material. In addition, there needs to be continued work on the use of isolated vascular tissue to probe dopamine receptors. 

First, radiolabeled ligands are bound to receptor material in as specific a manner as possible ligands of high affinity are required with dissociation... 

If one accepts that the concept of an isolated receptor is meaningful (i.e., that a receptor retains its integrity outside its in vivo environment), then attempts to achieve this condition must form an important step in receptor investigations. To date, only modest progress has been made in attempts to isolate opioid receptor material as characterized by its ability to bind ligands in a manner similar to that of intact nervous tissue. The problem is to devise a method of solubilizing the receptor from its supporting tissue (usually assumed to be a coll membrane) in a manner in which it retains its ability to... 

The supramolecular binding motifs described here were also used to attach catalysts to solid (silica) supports (128). The active metal complex could be switched from palladium to rhodium by using a polar solvent that breaks up the binding of the supramolecular motif. Allylic alkylation and hydroformylation catalysis could be carried out by using the same support "receptor" material and different "guest" ligands for the two metals a... 

Buhlmann, K. Schlatt, B. Cammann, K. Shulga, A., Plasticised polymeric electrolytes New extremely versatile receptor materials for gas sensors (VOC monitoring) and electronic noses (odour identification discrimination), Sens. Actuators B 1998, 49, 156-165. 

The presence of progesterone receptors in cancerous tissue improves the diagnosis of the disease, as there is an inverse relationship between the concentration of progesterone receptor material and the frequency of the metastasis [48]. Patients with oestrogen and progesterone receptors have about 75-80% chance of responding to hormonal therapy [49]. 

A major obstacle to a productive virus infection is the cell surface. Only certain cell types have the appropriate lipoproteins on their periphery which can act as receptor material for a particular picomavirus (6). This receptor material serves as an adsoipition site for the virus, the initial virus interaction with the host, and the first step in the infective process. The cell... 

Implantation reactions are interesting because of their similarity as regards reaction mechanisms to hot atom reactions. (However, some features are specific to recoil implantation reactions.) Ion implantation-induced chemical reactions have such features as well, but difficulty hes in keeping surface temperature as low as possible and in obtaining radioactive beams without contamination by other stable isotopes (which may result in severe damage in the target substance). These demerits restricted usefidness of ion implantation. Recoil implantation can be performed simply in the mixture of a recoil source and a catcher (receptor) material. In some cases, thin films of source and catcher could be combined in order to control recoil energy. 

Embryonic chick neutral retina, when grown in culture, releases into the media glycoprotein ligands which bind to homologous cells, and inhibits the lectin-induced redistribution of cell-surface receptors. Material with identical activity was released from neural retina cells that were treated with trypsin. 

Cuatrecasas, P., and Hollenberg, M. D., 1975, Binding of insulin and other hormones to non-receptor material. Saturability, specificity and apparent negative cooperativity, Biochem. Biophys. Res. Commun. 62 31. 

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