Molecular cloning and evolutionary analysis of GJB6 in mammals

GJB6 plays a crucial role in hearing. In mammals, bats use ultrasonic echolocation for orientation and locating prey. To investigate the evolution of GJB6 in mammals, we cloned the full-length coding region of GJB6 from 16 species of bats and 4 other mammal species and compared them with orthologous sequences in 11 other mammals. The results show purifying selection on GJB6 in mammals, as well as in the bat lineage, which indicates an important role for GJB6 in mammal hearing. We also found one unique amino acid substitution shared by 16 species of bats and 10 shared by two species of artiodactyls. This positioned the artiodactyls at an abnormal location in the gene tree. In addition, the cytoplasmic loop and carboxy terminus were more variable than other domains in all the mammals. These results demonstrate that GJB6 is basically conserved in mammals but has undergone relatively rapid evolution in particular lineages and domains.