. "The alpha-1 (\u03B11) adrenergic receptor is a G protein-coupled receptor (GPCR) associated with the Gq heterotrimeric G-protein. It consists of three highly homologous subtypes, including \u03B11A-, \u03B11B-, and \u03B11D-adrenergic. Catecholamines like norepinephrine (noradrenaline) and epinephrine (adrenaline) signal through the \u03B11-adrenergic receptor in the central and peripheral nervous systems."@en .