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The Journal of Biological Chemistry Mar 1986Human platelet alpha 2-adrenergic receptors have been purified approximately 80,000-fold to apparent homogeneity by a five-step chromatographic procedure. The overall...
Human platelet alpha 2-adrenergic receptors have been purified approximately 80,000-fold to apparent homogeneity by a five-step chromatographic procedure. The overall yield starting from the membranes is approximately 2%. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of radioiodinated protein from purified receptor preparations shows a single major band of Mr 64,000. The specific binding activity of the alpha 2-adrenergic receptor after four chromatographic steps is 14.5 nmol/mg protein. This value is consistent with the expected theoretical specific activity (15.6 nmol/mg) for a protein with a molecular mass of 64,000 daltons if it is assumed that there is one ligand-binding site/receptor molecule. The purified protein can be covalently labeled with the alkylating alpha-adrenergic ligand, [3H]phenoxybenzamine. This labeling is specific, and it shows that the Mr 64,000 protein contains the ligand binding site of the alpha 2-adrenergic receptor. In addition, the competitive binding of ligands to the purified receptor protein shows the proper alpha 2-adrenergic specificity. The alpha 2-adrenergic receptor contains an essential sulfhydryl residue. Thus, exposure of the purified receptor to the sulfhydryl-specific reagent, phenylmercuric chloride, resulted in an 80% loss of binding activity. This loss of binding activity was prevented when exposure to phenylmercuric chloride was done in the presence of alpha 2-adrenergic ligands, and it was reversed by subsequent exposure to dithiothreitol. Partial proteolysis of purified alpha 2-adrenergic receptors was obtained with Staphylococcus aureus V-8 protease, alpha-chymotrypsin, and papain. In a comparison with purified beta 2-adrenergic receptors, no common partial proteolytic products were found.
Topics: Blood Platelets; Chromatography, Affinity; Digitonin; Electrophoresis, Polyacrylamide Gel; Humans; Molecular Weight; Phenoxybenzamine; Phentolamine; Phenylmercury Compounds; Receptors, Adrenergic, alpha; Sepharose; Solubility; Sulfhydryl Compounds; Tritium
PubMed: 3005306
DOI: No ID Found -
Molecular Pharmacology Mar 1994The beta 2-adrenergic receptor undergoes isomerization between an inactive conformation (R) and an active conformation (R*). The formation of the active conformation of...
The beta 2-adrenergic receptor undergoes isomerization between an inactive conformation (R) and an active conformation (R*). The formation of the active conformation of the receptor molecule can be promoted by adrenergic agonists or by mutations in the third cytoplasmic domain that constitutively activate the receptor. Here we show that, of several beta-adrenergic receptor-blocking drugs tested, only two, ICI 118551 and betaxolol, inhibit the basal signaling activity of the beta 2-adrenergic receptor, thus acting as negative antagonists. We document the molecular properties of the more efficacious ICI 118551; (i) it shows higher affinity for the inactive form of the receptor and (ii) it inhibits the spontaneous formation of a beta-adrenergic receptor kinase substrate by the receptor. These properties are opposite those of adrenergic agonists, indicating that, in a fashion reciprocal to that of agonists, negative antagonists promote the formation of an inactive conformation of the receptor.
Topics: Adrenergic beta-Antagonists; Allosteric Site; Animals; Baculoviridae; Betaxolol; Binding Sites; CHO Cells; Cricetinae; Lepidoptera; Phosphorylation; Propanolamines; Protein Conformation; Receptors, Adrenergic, beta; Signal Transduction
PubMed: 7908404
DOI: No ID Found -
Angewandte Chemie (International Ed. in... Oct 2013
Topics: Adrenergic beta-2 Receptor Agonists; Fluorine Radioisotopes; Humans; Nuclear Magnetic Resonance, Biomolecular; Receptors, Adrenergic, beta-2; Thermodynamics
PubMed: 23956158
DOI: 10.1002/anie.201305286 -
Transactions of the Association of... 1991
Review
Topics: Adrenergic alpha-Antagonists; Amino Acid Sequence; Animals; Binding Sites; Humans; Molecular Sequence Data; Point Mutation; Receptors, Adrenergic, alpha; Receptors, Adrenergic, beta
PubMed: 1688262
DOI: No ID Found -
Psychopharmacology Jun 2004The cognitive functions of the prefrontal cortex (PFC) are profoundly impaired in schizophrenic patients. Although dopamine has been the major focus of schizophrenia... (Review)
Review
RATIONALE
The cognitive functions of the prefrontal cortex (PFC) are profoundly impaired in schizophrenic patients. Although dopamine has been the major focus of schizophrenia research, norepinephrine (NE) also has marked influences on PFC cognitive functioning.
OBJECTIVE
This review aims to identify the adrenergic receptors which may be appropriate targets for therapeutic actions in schizophrenia.
METHODS
Studies of adrenergic mechanisms influencing PFC function in animals and humans were reviewed.
RESULTS
Modest levels of NE engage postsynaptic alpha(2A)-adrenergic receptors and strengthen working memory. These beneficial effects have been observed at both the behavioral and cellular levels in animals, and have translated to the clinic in patients with PFC impairments. Thus, the alpha(2A)-adrenergic receptor is a proven molecular target. In contrast, high levels of NE released during stress impair PFC cognitive function via activation of protein kinase C intracellular signaling, a pathway increasingly associated with the etiology of schizophrenia. Blockade of alpha(1) adrenoceptors or inhibition of protein kinase C helps to protect PFC cognitive function in animals, and may have similar therapeutic actions in humans. Blockade of the alpha(2C) receptor may also be helpful in enhancing catecholamine release while blocking detrimental DA actions in striatum.
CONCLUSION
Highly selective adrenergic agents may be useful for enhancing PFC function in schizophrenic patients
Topics: Adrenergic Agents; Animals; Cognition Disorders; Humans; Models, Neurological; Prefrontal Cortex; Receptors, Adrenergic; Schizophrenia
PubMed: 15205875
DOI: 10.1007/s00213-003-1724-3 -
Pharmacogenetics Apr 2001
Topics: GTP-Binding Proteins; Humans; In Vitro Techniques; Polymorphism, Genetic; Receptors, Adrenergic, beta; Signal Transduction
PubMed: 11337933
DOI: 10.1097/00008571-200104000-00001 -
Pulmonary Pharmacology Feb 1995
Review
Topics: Asthma; Humans; Point Mutation; Polymorphism, Genetic; Receptors, Adrenergic, beta-2; Signal Transduction
PubMed: 8535093
DOI: 10.1006/pulp.1995.1001 -
The Journal of Biological Chemistry Jul 1983The beta-adrenergic receptor photoaffinity ligand p-azido-m-[125I]iodobenzylcarazolol has been used to covalently label the beta 1 and beta 2 adrenergic receptor binding...
The beta-adrenergic receptor photoaffinity ligand p-azido-m-[125I]iodobenzylcarazolol has been used to covalently label the beta 1 and beta 2 adrenergic receptor binding subunits present in left ventricular myocardial membranes derived from mammalian (including human) and nonmammalian species. Covalent incorporation of the photoaffinity ligand into membrane proteins was followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In the case of the human, canine, porcine, rabbit, and rat left ventricle, all of which contain predominantly or exclusively beta 1-adrenergic receptors, two peptides of Mr approximately equal to 62,000 (major component) and Mr approximately equal to 55,000 (minor component) were specifically labeled and visualized by autoradiography. Photoincorporation into these two bands could be blocked with the appropriate drugs to display a beta 1-adrenergic receptor pharmacological specificity. Simultaneous sodium dodecyl sulfate-polyacrylamide gel electrophoresis of samples from each species revealed that all of the Mr = 62,000 peptides co-migrated suggesting similarity in the beta 1-adrenergic receptor binding subunit peptides in all of these species. The minor component Mr approximately equal to 55,000 appears to be a proteolytic degradation product of the Mr = to 62,000 peptide. Its formation could be decreased by proteinase inhibitors. This suggests that the heterogeneity of the labeling pattern observed in mammalian tissues in this and previous studies may be the result of proteolytic degradation of the receptor subunit which occurs during membrane preparation. Photoaffinity labeling of frog ventricular membranes which contain predominantly beta 2-adrenergic receptors also revealed two peptides of Mr approximately equal to 62,000 (major component) and 55,000 (minor component) with the pharmacological selectivity of a beta 2-adrenergic receptor. These data suggest marked similarities in the beta 1- and beta 2-adrenergic receptor binding subunits of different species and suggest that the pharmacological subtype might be determined by the detailed structure, i.e. amino acid sequence, at the ligand binding sites of the receptor peptide.
Topics: Adult; Affinity Labels; Animals; Azides; Binding, Competitive; Cell Membrane; Dogs; Heart Ventricles; Humans; Iodine Radioisotopes; Kinetics; Molecular Weight; Myocardium; Propanolamines; Rana pipiens; Rats; Receptors, Adrenergic; Receptors, Adrenergic, beta; Species Specificity; Structure-Activity Relationship
PubMed: 6305985
DOI: No ID Found -
The American Journal of Physiology Apr 1997In disease states such as heart failure, catecholamines released from sympathetic nerve endings and the adrenal medulla play a central role in the adaptive and... (Review)
Review
In disease states such as heart failure, catecholamines released from sympathetic nerve endings and the adrenal medulla play a central role in the adaptive and maladaptive physiological response to altered tissue perfusion. G protein-coupled receptors are importantly involved in myocardial growth and the regulation of contractility. The adrenergic receptors themselves are regulated by a set of specific kinases, termed the G protein-coupled receptor kinases. The study of complex systems in vivo has recently been advanced by the development of transgenic and gene-targeted "knockout" mouse models. Combining transgenic technology with sophisticated physiological measurements of cardiac function is an extremely powerful strategy for studying the regulation of myocardial contractility in normal animals and in models of disease states. The purpose of this review is to summarize current knowledge about the regulation of cardiovascular homeostasis involving signaling pathways through stimulation of adrenergic receptors.
Topics: Animals; Cardiomegaly; Genetic Engineering; Heart; Heart Diseases; Heart Failure; Humans; Major Histocompatibility Complex; Mice; Mice, Knockout; Mice, Transgenic; Receptors, Adrenergic; Receptors, Adrenergic, alpha-1; Receptors, Adrenergic, alpha-2; Receptors, Adrenergic, beta; Receptors, Adrenergic, beta-1; Receptors, Adrenergic, beta-2; Receptors, Adrenergic, beta-3; Signal Transduction
PubMed: 9139936
DOI: 10.1152/ajpheart.1997.272.4.H1553 -
Brain, Behavior, and Immunity Dec 2002The catecholamines norepinephrine and epinephrine are used by the sympathetic nervous system to communicate with other organ systems, including the immune system.... (Review)
Review
The catecholamines norepinephrine and epinephrine are used by the sympathetic nervous system to communicate with other organ systems, including the immune system. Adrenergic receptors on target cells bind these catecholamines and modulate the activity of the target cell. The beta 2-adrenergic receptor is the most abundantly expressed and best studied adrenergic receptor in the immune system. Here, I summarize data from our own laboratory and from others on the expression and possible function of alpha 1-adrenergic receptors in the immune system. alpha 1-Adrenergic receptor expression in the immune system can be regulated by glucocorticoids, by beta 2-adrenergic agonists, and by cytokines. In addition, the possible pathophysiological implications of the expression of alpha 1-adrenergic receptors on immune cells from arthritis patients are discussed.
Topics: Animals; Gene Expression Regulation; Humans; Immune System; Receptors, Adrenergic, alpha-1; Sympathetic Nervous System
PubMed: 12480508
DOI: 10.1016/s0889-1591(02)00033-8