The function of GJA1 (gap junction protein alpha 1, Ensembl gene identifier ENSG00000152661) is as follows. Structural component of the gap junction, a specialized intercellular structure consisting of a cluster of closely packed pairs of transmembrane channels, the connexons, that allow passage of small molecules and electrical signals between neighboring cells (By similarity). Forms homotypic and heterotypic channels gated by transjunctional voltage (By similarity). May play a critical role in the physiology of hearing by participating in the recycling of potassium to the cochlear endolymph (Probable). Negative regulator of bladder functional capacity: acts by enhancing intercellular electrical and chemical transmission, thus sensitizing bladder muscles to cholinergic neural stimuli and causing them to contract (By similarity). May play a role in the conductive system of ventricular myocardium and heart morphogenesis (By similarity). May play a role in cell growth inhibition through the regulation of NOV expression and localization (By similarity). Involved in intercellular innate immune signaling (PubMed:24077100, PubMed:31992625, PubMed:40010341). Mediates translocation of 2',3'-cGAMP and 2',5'-oligoadenylates (2-5A) second messengers from virus-infected cells to macrophages and uninfected neighboring cells to propagate and amplify the antiviral immune response (PubMed:24077100, PubMed:31992625, PubMed:40010341). {ECO:0000250|UniProtKB:P08050, ECO:0000250|UniProtKB:P23242, ECO:0000269|PubMed:24077100, ECO:0000269|PubMed:31992625, ECO:0000269|PubMed:40010341, ECO:0000305|PubMed:11741837}.