The function of GJB2 (gap junction protein beta 2, ENSG00000165474) is as follows. Structural component of gap junctions (PubMed:16849369, PubMed:17551008, PubMed:19340074, PubMed:19384972, PubMed:21094651, PubMed:26753910). Gap junctions are dodecameric channels that connect the cytoplasm of adjoining cells. They are formed by the docking of two hexameric hemichannels, one from each cell membrane (PubMed:17551008, PubMed:19340074, PubMed:21094651, PubMed:26753910). Small molecules and ions diffuse from one cell to a neighboring cell via the central pore (PubMed:16849369, PubMed:19384972, PubMed:21094651). {ECO:0000269|PubMed:16849369, ECO:0000269|PubMed:17551008, ECO:0000269|PubMed:19340074, ECO:0000269|PubMed:19384972, ECO:0000269|PubMed:21094651, ECO:0000269|PubMed:26753910}.