Solubilization, membrane receptors

Venter JC, I larrison LC. Membranes, Detergents and Receptor Solubilization, Alan R. Liss, New York, 1984. 

Summary of ligand, G protein, and receptor-binding data from previous studies with receptor proteins extracted from U937 cell membranes and solubilized in 1% DOM... 

Effect of Guanine Nucleotides on High Affinity Agonist Binding to Membrane and Solubilized Receptor Preparations... 

As indicated earlier, the intent of this section was not to be global with respect to the scope of its coverage, but rather to discuss in general terms some considerations common to the study of ligands which interact with membrane receptors and, thereby, elicit post-binding events. Many of the examples chosen have been drawn from my experience with the follitropin-gonadal receptor system, but they provide instances of problems, concerns and caveats in use of techniques and interpretation of results that are common to this particular field of study. The reader is referred to the specific examples of hormone receptor interactions to follow, wherein aspects of the problems not germaine to this section, such as, for example, techniques for purification of solubilized receptors, are considered in detail. 

B. thuringiensis crystals are first solubilized in the midgut of susceptible insects, followed by activation of the protoxins to active toxins by midgut proteases. The activated toxins then bind to midgut membrane receptors, insert into the apical membrane and form pores. Formation of the pores causes loss of osmotic regulation, and eventually leads to cell lyses, which is thought to be responsible for insect death [4,5]. 

Solubilized surface proteins from normal human lymphocytes have been obtained by mild digestion with trypsin, and the binding of these components to labelled Ricinus sanguineus has been studied.A method for the direct visualization of lymphocyte membrane receptors has made use of fluoresceinyl derivatives of glycosylated cytochemical markers such as bovine serum albumin covalently attached to either D-mannose, 2-acetamido-2-deoxy-D-galactose, L-fucose, or lactose. 

Ruoho AE, Rashidbaigi A, Roeder PE (1984) In Venter JC, Harrison LC (eds) Receptor biochemistry and methodology, vol 1 membranes, detergents and receptor solubilization. Liss, New York, p 119... 

It can be seen then that the metabolic state of the cell is an important factor influencing surface membrane functions. Where viral transformation causes cancer-like properties, metabolic control at the nucleic acid level is likely, although viral-host interactions seem more complex than first theorized (Altman and Katz, 1976). Receptors for enteroviruses have been reported and shown to be specific for various viral strains. Susceptibility to viral infection is correlated with the presence of receptor sites on intracellular membranes as well as on the cell surface. Chemically, virus receptors solubilized from plasma membranes have been determined to be lipoproteins, with the protein moiety being most important in determining receptor activity (McLaren et al., 1968). A review of cell membrane receptors for viruses, antigens and... 

Eldefrawi, M. E., A. T. Eldefrawi, N. A. Mansour, J. W. Daly, B. Witkop, and E. X. Albuquerque Acetylcholine receptor and ionic channel of Torpedo electroplax Binding of perhydrohistrionicotoxin to membrane and solubilized preparations. Biochemistry 17, 5474—5484 (1978). 

Hjelmeland, L.M. and Chrambach, A. (1984) Solubilization of functional membrane-bound receptors, in Membranes, Detergents and Receptor Solubilization (eds C.J. Venter and L.C. Harrison), Alan R. Liss, New York, pp. 35-46. 

Radioiodinated derivatives have been prepared to define more closely the target site of a-conotoxins on the acetylcholine receptor (R. Myers, unpublished data). In membrane preparations from Torpedo electroplax, photoactivatable azidosalicylate derivatives of a-conotoxin GIA preferentially label the p and 7 subunits of the acetylcholine receptor. However, when the photoactivatable derivative is cross-linked to detergent solubilized acetylcholine receptor (AChR), only the 7 subunit is labeled. Since snake a-neurotoxins mainly bind to the a subunits of AChR and a-conotoxins compete directly with a-bungarotoxin, the cross-linking results above are both intriguing and problematic. 

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