THE CHARACTERISTIC

THE CHARACTERISTIC OF RECEPTORS OF HORMONES Researches on the linkage, spent with the help radioactive atoms of hormones, have allowed to tap some prominent features inherent to receptors many of hormones. Universal line of receptors is their ability to distinguish and bind corresponding chemical transmitters buy cipro 500 mg or hormones in the presence of excess of molecules of other kinds. This property is easily shown in the presence of a labelled hormone as selective reaction of linkage with high affinity which leads to formation specific a complex. For the last years such interactions were observed in many tissues. In many researches presence of specific binding places in corresponding target tissues accepted for the proof of presence of hormonal receptors. Specific binding places are found out also in cells as which it is not accepted to consider as cells-targets, for example receptors of insulin and in lymphocytes, Prolactinum receptors in a liver and adrenals. If to consider, that correct representation about receptors assumes presence not only distinguishing, but also a component starting reaction under such definition receptors for which functional reaction while remains not found out, and also receptors which are allocated do not approach, or are located on nonreacting cellular components. Thus, the receptor is characterised by specific linkage and ability to transfer a signal even if distal elements of reaction are absent or . The fullest representation about a receptor a hormone includes double functional properties: superficial recognition and translation interactions in specific biological reaction. Irrespective of, whether secretion of peptides, a steroidogenesis, reduction or transport of ions, the mechanisms mediating hormonal effect is cellular reaction, usually include change of calcium streams and a metabolism of cyclic nucleotides.
On membranous fractions or intact cells of many target tissues observed dependence between linkage of a hormone and biochemical reactions. Correlation between a saturation of receptors and activity of adenylatecyclase is shown on preparations of membranes of many cells, for example cells of an adrenal in case of action , a liver in case of action of a glucagon, kidneys at addition of a vasopressin, erythrocytes of birds under the influence of catecholamins, seed canaliculuses in the presence of , and also spermaries and ovaries in the presence of and . In intact tissues and the isolated cells-targets hormone linkage also correlated with synthesis and liberation [6]. Correlation of linkage of a hormone with the subsequent cellular reactions observed concerning insulin and glucose oxidation in fatty cells or transport of amino acids order acomplia rimonabant in thymocytes, catecholamins and sodium transport in erythrocytes. and production of androgens spermaries, and also angiotensin II and production of Aldosteronum cells of a glomerular zone of an adrenal. Sometimes believe, that it is necessary to name hormonal receptors only those binding places of a tissue which can be identified with certain biochemical reaction. However specific linkage labelled under condition of observance of adequate demands to a technique of its definition all is the weighty indicating on presence of hormonal receptors. Such demands concern use of a labelled hormone with distinct biological activity (received with the help or ), an exact estimation of nonspecific linkage and an exception of linkage with blasting or others enzymatic , present at fabric fractions. The majority of receptors hormones shows high specificity in relation to biologically active hormones or their derivatives, the high affinity of linkage characterised by constants; Equilibriums of association of an order 109-1011 ~1, and saturability at rather low concentration of a hormone. Last properties correspond to low concentration of hormonal receptors in a target tissue which makes usually all a little thousand places on a cell. Linkage reaction always depends on temperature, differs high rate and in cell-free preparations is usually reversible. In intact cells the irreversible component of linkage of a hormone recently has been found out, and for Thrombinum and the factor of growth of a false skin () covalent joining to a receptor has been shown. Exact definition of constants of linkage and thermodynamic properties of receptors often is at a loss that in experiences on the linkage, spent in vitro at physiological temperatures, hormone and receptor degradation can take place. In the conditions inherent to experiments in vivo, also it is difficult to study kinetic and binding properties of receptors of hormones. On rate of association and hormone dissociation the big influence is rendered by temperature, and a circuit of molecules of a hormone in places at characteristic for an organism temperature and perfusion conditions is studied insufficiently. The albuminous nature of receptors of polypeptide hormones on a plasmatic membrane is proved by their splitting under the influence of various proteolytic enzymes and peptidases.