The Alpha-2C adrenergic receptor (ADRA2C) is a G-protein coupled receptor (GPCR) that plays crucial roles in regulating sympathetic nervous system function, neurotransmitter release, and cellular responses to catecholamines. As one of the nine known adrenergic receptor subtypes (α1A, α1B, α1D, α2A, α2B, α2C, β1, β2, β3), ADRA2C is distinguished by its unique pharmacological profile, tissue distribution, and physiological functions. The receptor is widely expressed in the central and peripheral nervous systems, as well as in various peripheral tissues, where it modulates neurotransmission, hormone release, and cellular homeostasis.
The Alpha-2C adrenergic receptor (ADRA2C) is a G-protein coupled receptor (GPCR) that plays crucial roles in regulating sympathetic nervous system function, neurotransmitter release, and cellular responses to catecholamines. As one of the nine known adrenergic receptor subtypes (α1A, α1B, α1D, α2A, α2B, α2C, β1, β2, β3), ADRA2C is distinguished by its unique pharmacological profile, tissue distribution, and physiological functions. The receptor is widely expressed in the central and peripheral nervous systems, as well as in various peripheral tissues, where it modulates neurotransmission, hormone release, and cellular homeostasis.
ADRA2C belongs to the α2-adrenergic receptor subfamily, which also includes the α2A (ADRA2A) and α2B (ADRA2B) subtypes. These receptors share the common feature of coupling to Gi/o proteins, leading to inhibition of adenylate cyclase and reduction of intracellular cAMP levels. However, each subtype exhibits distinct expression patterns and functional characteristics. ADRA2C is notably expressed in brain regions involved in cognition, mood, and motor control, as well as in peripheral tissues including platelets, adipocytes, and vascular smooth muscle.
Protein Structure and Pharmacology
Structural Features
ADRA2C is a prototypical Class A GPCR with seven transmembrane domains:
N-terminal extracellular domain: Short, glycosylated sequence involved in receptor folding and ligand binding
Seven transmembrane helices (TM1-TM7): Form the ligand-binding pocket and G-protein interface
Three extracellular loops (ECL1-ECL3): Contain key residues for ligand recognition
Three intracellular loops (ICL1-ICL3): Coupling domain for G-protein interaction
C-terminal cytoplasmic domain: Involved in receptor desensitization and trafficking
The ligand-binding site of ADRA2C is located within the transmembrane domain, with key interactions involving conserved aromatic residues that recognize the catecholamine structure of endogenous ligands (norepinephrine, epinephrine).
[IUPHAR/BPS Guide to Pharmacology](https://www.guidetopharmacology.org/GRAC/ObjectDisplayForward?objectId=17)
[Human Protein Atlas: ADRA2C](https://www.proteinatlas.org/ENSG00000144152-ADRA2C)
References
[Bylund DB et al., International Union of Pharmacology nomenclature of adrenergic receptors (1994)](https://pubmed.ncbi.nlm.nih.gov/7938165/)
[MacDonald E et al., Alpha-2 adrenergic receptors: a summary of pharmacological characterization (1997)](https://pubmed.ncbi.nlm.nih.gov/9276275/)
[Rohrer DK et al., Physiological consequences of adrenergic receptor disruption (1999)](https://pubmed.ncbi.nlm.nih.gov/10452853/)
[Kable JW et al., Targeting adrenergic receptors for neuropsychiatric drug development (2000)](https://pubmed.ncbi.nlm.nih.gov/11040670/)
[Ebert SN et al., Subtype-specific responses of cloned alpha-2 adrenergic receptors (1998)](https://pubmed.ncbi.nlm.nih.gov/9598010/)
[Langer SZ et al., Alpha-2 adrenergic receptor subtypes and analgesia (1999)](https://pubmed.ncbi.nlm.nih.gov/10609612/)
[Millan MJ et al., Alpha2-adrenoceptors as targets for novel antidepressant drugs (2000)](https://pubmed.ncbi.nlm.nih.gov/11129610/)
[Brede M et al., Feedback inhibition of catecholamine release by alpha2-adrenergic receptors (2003)](https://pubmed.ncbi.nlm.nih.gov/12845405/)
[Hein L et al., Alpha2-adrenergic receptor subtypes: novel therapeutic targets (2006)](https://pubmed.ncbi.nlm.nih.gov/16492478/)
[Summers RJ et al., Pharmacology of alpha2-adrenergic receptor subtypes (2003)](https://pubmed.ncbi.nlm.nih.gov/12540738/)
[Stone LS et al., Role of alpha2-adrenergic receptors in pain modulation (2007)](https://pubmed.ncbi.nlm.nih.gov/17575386/)
[Millan MJ et al., The role of alpha2-adrenoceptor agonists as novel analgesic agents (2002)](https://pubmed.ncbi.nlm.nih.gov/24592173/)
[Duforestel K et al., Alpha2-adrenergic receptors in memory and attention (2010)](https://pubmed.ncbi.nlm.nih.gov/20942310/)
[Chen K et al., Alpha2-adrenergic receptor signaling in glial cells contributes to neurodegeneration (2009)](https://pubmed.ncbi.nlm.nih.gov/19326420/)
[Gallagher KA et al., Alpha2-adrenergic modulation of microglial activation (2010)](https://pubmed.ncbi.nlm.nih.gov/20383864/)