Adrenergic Receptor Article Index for
Adrenergic
 

Information About

Adrenergic Receptor




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The adrenergic receptors (or '''adrenoceptors''') are a class of G Protein-coupled Receptor s that are targets of the Catecholamine s. Adrenergic Receptor s specifically bind their Endogenous Ligand s, the catecholamines Adrenaline and Noradrenaline (called Epinephrine and Norepinephrine in the USA ), and are activated by these.

Many cells possess these receptors, and the binding of an Agonist will generally cause the cell to respond in a Fight-or-flight manner. For instance, the Heart Rate will increase and the Pupil s will dilate, energy will be mobilized, and blood flow diverted from other organs to Skeletal Muscle .(Note: Sympathetic activity will result in vasoDILATION of coronary arteries via the Beta-2 adrenergic receptors.)


SUBTYPES OF ADRENERGIC RECEPTORS

There are several types of adrenergic receptors, but there are two main groups: α-Adrenergic and β-Adrenergic.
  • α receptors bind norepinephrine and epinephrine, though norepinephrine has higher affinity. Phenylephrine is a selective agonist of the α receptor.

  • β receptors are linked to Gs Proteins , which in turn are linked to Adenylyl Cyclase . Agonist binding thus causes a rise in the intracellular concentration of the second messenger CAMP . Downstream effectors of cAMP include CAMP-dependent Protein Kinase (PKA), which mediates some of the intracellular events following hormone binding.



COMPARISON


The absence of "ADRA1C" is intentional. At one time, there was a subtype known as C, but was found to be one of the previously discovered subtypes. To avoid confusion, it was decided that there would never be a C subtype again and so if any new subtypes were discovered, naming would start with D.


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