Alpha(1)-adrenergic receptor

The alpha(1)-adrenergic receptor (α1-AR) is a G-protein coupled receptor that primarily mediates physiological responses to norepinephrine and epinephrine. There are three subtypes: α1A, α1B, and α1D. They couple to Gq/11 proteins, stimulating phospholipase C, leading to increased intracellular calcium and smooth muscle contraction. Drugs targeting these receptors are used for hypertension, BPH, heart failure, glaucoma, sexual dysfunctions, and some cancers. Alternative splicing can generate isoforms with different C-terminal regions.

Agonist binding stimulates phospholipase C via Gq/11, leading to increased intracellular calcium and activation of protein kinase C pathways, resulting in smooth muscle contraction and vasoconstriction. Antagonists block the receptor, preventing agonist binding and subsequent signaling.