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α1B-adrenoceptor

Previous and Unofficial Names
α1b
Structural Information
class A G protein-coupled receptor
Species TM AA Chromosomal Location Gene Name Reference
Human 7 519 5q23-q32 ADRA1B 31
Rat 7 514 10q21 Adra1b 30
Mouse 7 515 11 B1.1 Adra1b 32
Contents:
Previous and Unofficial Names
Structural Information
Database Links
Agonists
Antagonists
Allosteric Regulators
Transduction Mechanisms
Tissue Distribution
Functional Assays
Physiological Functions
Physiological Consequences of Altering Gene Expression
Database Links
ChEMBL Target 128 (Hs), 10652 (Mm), 12474 (Rn)
Ensembl ENSG00000170214 (Hs), ENSMUSG00000050541 (Mm)
Entrez Gene 147 (Hs), 11548 (Mm), 24173 (Rn)
GeneCards ADRA1B (Hs)
HomoloGene 55477 (Hs)
OMIM 104220 (Hs)
PharmGKB Gene PA33 (Hs)
Protein Ontology (PRO) PRO:000001184 (Hs)
RefSeq Nucleotide NM_000679 (Hs), NM_007416 (Mm), NM_016991 (Rn)
RefSeq Protein NP_000670 (Hs), NP_031442 (Mm), NP_058687 (Rn)
UniGene Hs. 368632 (Hs)
UniProt P35368 (Hs), P15823 (Mm), P97717 (Rn)
Wikipedia α1B-adrenoceptor
Search for 3D structures on the PDB
Search using keywords: Adrenoceptors alpha1B-adrenoceptor Search using accession numbers: P97717 || P35368 || P15823
Agonists
Key to terms and symbols View all chemical structures Click column headers to sort
Ligand Sp. Action Affinity Units Reference
[125I]-HEAT Hs Full agonist 10.2 pKd 17
(-)-adrenaline Hs Full agonist 6.5 pKi 17
oxymetazoline Hs Full agonist 6.5 pKi 17,19
(-)-noradrenaline Hs Full agonist 6.2 pKi 17
NS-49 Hs Partial agonist 5.1 pKi 19
(±)-adrenaline Hs Full agonist 5.1 pKi 17
methoxamine Hs Full agonist 4.0 pKi 17
phenylephrine Hs Full agonist 6.3 – 7.5 pIC50 4,34
Agonist Comments
Non catecholamine agonists, such as methoxamine and amidephrine, have both low affinity and low intrinsic activity at the α1B- adrenoceptor [34]. Much data has been generated using the hamster α1B-adrenoceptor, since this was the first α1B- homolog to be cloned. There is no evidence for any significant species differences in agonist and antagonist affinity between hamster, rat and human receptors.
Antagonists
Key to terms and symbols View all chemical structures Click column headers to sort
Ligand Sp. Action Affinity Units Reference
[125I]BE-2254 Hs Inverse agonist 9.9 pKd 5,29
(+)-cyclazosin Hs Inverse agonist 9.9 pKi 21
prazosin Hs Inverse agonist 9.6 – 9.9 pKi 4,17,27
tamsulosin Hs Inverse agonist 9.6 – 9.7 pKi 4,27
(-)-YM617 Hs Antagonist 9.5 pKi 17
NAN 190 Hs Antagonist 9.2 pKi 25
spiperone Hs Inverse agonist 9.2 pKi 25
WB 4101 Hs Antagonist 8.5 – 9.0 pKi 4,17
rho-TIA Hs Antagonist 8.4 pKi 33
A-119637 Hs Antagonist 8.3 pKi 26
L-765314 Rn Antagonist 8.3 pKi 46
clozapine Hs Antagonist 8.2 pKi 25
ketanserin Hs Antagonist 8.2 pKi 25
A-123189 Hs Antagonist 8.0 pKi 26
risperidone Hs Antagonist 8.0 pKi 25
ritanserin Hs Antagonist 8.0 pKi 25
Rec 15/2739 Hs Antagonist 7.8 pKi 4
KMD-3213 Hs Antagonist 7.7 pKi 17
L-765314 Hs Antagonist 7.7 pKi 46
cyproheptadine Hs Antagonist 7.6 pKi 25
spiroxatrine Hs Antagonist 7.6 pKi 25
phentolamine Hs Antagonist 7.5 pKi 17
5-methylurapidil Hs Antagonist 7.2 – 7.7 pKi 4,17,25
indoramin Hs Antagonist 7.4 pKi 4
mianserin Hs Antagonist 7.4 pKi 25
BMY-7378 Hs Antagonist 7.0 – 7.5 pKi 25-26
(+)-niguldipine Hs Antagonist 6.7 – 7.7 pKi 4,17
Ro-70-0004 Hs Antagonist 7.1 pKi 27
View species-specific antagonist tables
Antagonist Comments
(+) Cyclazosin shows α1B- selectivity in radioligand binding assays with recombinant receptors; however, a lack of functional selectivity in isolated tissue preparations has been reported [35]. A 19 amino acid peptide, rho-TIA, has been reported to produce non-competitive blockade of α1B-adrenoceptor mediated inositol phosphate formation at concentrations having little effect on this response in cells expressing the other α1 subtypes. Higher concentrations produce nearly complete blockade of the α1B- response, and competitive inhibition of the α1A- and α1D- mediated response [33].
Allosteric Regulator Comments
While no allosteric regulation of the α1B- adrenoceptor has been proven, the conopeptide sigma-TIA displaced radioligand binding to recombinant α1B- adrenoceptors in a non-competitive manner [2,33].

Explore drug-target interactions for this set of compounds using iPHACE

Primary Transduction Mechanisms
Transducer Effector/Response
Gq/G11 family Phospholipase C stimulation
Calcium channel
Other - See Comments
Comments:  The α1B-adrenoceptor is coupled to calcium release and inositol phosphate production less efficiently than the α1A but more efficiently than the α1D.
References:  2,5
Secondary Transduction Mechanisms
Transducer Effector/Response
Phospholipase D stimulation
Other - See Comments
Comments:  α1- adrenoceptors (all subtypes) can also activate protein Kinase C, mitogen activated protein kinases.
References:  2,5
Tissue Distribution
In the rat brain, highest levels of α1B- adrenoceptor protein are found in regions involved in stress and neuroendocrine function. Intense labeling was found in hypothalamic paraventricular nuclei, supraoptic nucleus, median eminence and arcuate nucleus. Immunoreactivity was also found in layer V of the frontal cortex, thalamus, hippocampus, diagonal band of Broca and caudate-putamen. Some midbrain and hindbrain regions important for motor function were also immunoreactive.
Species:  Rat
Technique:  Immunohistochemistry.
References:  9,39
High expression levels of α1B-adrenoceptor was found in the medial layer of the aorta and caudal, femoral, iliac, renal, superior mesenteric and mesenteric resistance arteries.
Species:  Rat
Technique:  Immunohistochemistry.
References:  40
α1B-adrenoceptors are either absent or scarce on human prostatic stromal smooth muscle, proximal urethra or corpus cavernosa. α1B-adrenoceptors are found in the human spleen and kidney, and with other subtypes in human somatic arteries and veins.
Species:  Human
Technique:  RT-PCR, RNase protection assay.
References:  5,10
Functional Assays
Isolated longitudinal strip of rat spleen.
Species:  Rat
Tissue:  Spleen
Response measured:  Contraction
References:  35
Isolated first order venules.
Species:  Human
Tissue:  Vasculature
Response measured:  Vasculature
References:  38
Physiological Functions
Contraction of mesenteric resistance arteries.
Species:  Rat
Tissue:  Vasculature.
References:  40
α1B-adrenoceptors appear to be involved in the regulation of cardiac growth and contractile function.
Species:  Mouse
Tissue:  Heart.
References:  41
Contraction of mammary artery and saphenous vein (with α1A).
Species:  Human
Tissue:  Vasculature
References:  38
Adrenaline induced stimulation of hydroxyl radical formation in isolated hepatocytes.
Species:  Rat
Tissue:  Liver.
References:  42
CNS Stimulation by d-amphetamine, cocaine and morphine.
Species:  Mouse
Tissue:  Brain.
References:  43
Growth of vascular adventitia following balloon injury.
Species:  Rat
Tissue:  Aorta.
References:  44
Contraction of umbilical vein.
Species:  Human
Tissue:  Vasculature.
References:  45
Physiological Consequences of Altering Gene Expression
α1B- knockout mice are protected against methamphetamine induced degeneration of the nigro-striatal neuronal pathway in CNS. α1B- knockout mice show an enhanced reactivity to new situations.
Species:  Mouse
Tissue: 
Technique:  Transgenesis.
References:  36
α1B- knockout mice have elevated glycogen stores in both fed and fasted state and are hyperinsulinemic when fasted. They are more sensitive to obesity induced by a high fat diet.
Species:  Mouse
Tissue: 
Technique:  Transgenesis.
References:  37

To cite this receptor data page, please use the following:

Richard A. Bond, David B. Bylund, Douglas C. Eikenburg, J. Paul Hieble, Rebecca Hills, Kenneth P. Minneman, Sergio Parra.
Adrenoceptors: α1B-adrenoceptor. Last modified on 2010-06-28. Accessed on 2010-09-03. IUPHAR database (IUPHAR-DB), http://www.iuphar-db.org/DATABASE/ObjectDisplayForward?objectId=23.


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