The function of ENSG00000120907 (ADRA1A, adrenoceptor alpha 1A) is as follows. Alpha-1 adrenergic receptors are G protein-coupled receptors for catecholamines that signal through the G(q) family of G proteins, including G(q) and G(11). Upon activation, they stimulate the phosphatidylinositol-calcium second messenger pathway, leading to calcium release from intracellular stores and activation of protein kinase C (PubMed:37563160). ADRA1A binds the catecholamine ligands norepinephrine and epinephrine (PubMed:18802028, PubMed:37563160, PubMed:7815325, PubMed:8024574, PubMed:8183249, PubMed:8832064). Can also couple to G(14) protein (By similarity). Nuclear ADRA1A forms heterooligomers with ADRA1B to regulate phenylephrine(PE)-stimulated ERK signaling in cardiac myocytes (PubMed:18802028, PubMed:22120526). At the plasma membrane, ADRA1A interacts with CAVIN4/MURC to regulates ERK activation in cardiomyocytes, contributing to the regulation of cardiac hypertrophy (PubMed:24567387). Additionally, functions as a vasopressor in resistance arteries and plays a role in maintaining normal arterial blood pressure (By similarity). {ECO:0000250|UniProtKB:P18130, ECO:0000250|UniProtKB:P97718, ECO:0000269|PubMed:18802028, ECO:0000269|PubMed:22120526, ECO:0000269|PubMed:24567387, ECO:0000269|PubMed:37563160, ECO:0000269|PubMed:7815325, ECO:0000269|PubMed:8024574, ECO:0000269|PubMed:8183249, ECO:0000269|PubMed:8832064}.