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The innexin gap-junction proteins: their discovery, role in electrical-synapse function, and evolutionary provenance.(3 pm, MAY 27, Monday)
Published:2013-05-20 Hits:973

Title: The innexin gap-junction proteins: their discovery, role in electrical-synapse function, and evolutionary provenance.


Speaker: Jonathan Bacon

                  School of Life Sciences, University of Sussex, UK(Web Page:


Time: 3 pm, MAY 27 (Monday), 2013


Place: Room 2201, East Guanghua Tower



In flies, escape behaviour is mediated by the neurons of the Giant-Fibre System, in which the Giant Fibre (GF) forms an electrical synapse with the Tergotrochanteral Motoneuron (TTMn). In flies carrying the shaking B2 mutation, dye coupling is disrupted between the GF and TTMn, indicating that the shaking B gene is required for electrical-synapse formation in the GF system. Expression of Shaking B in Xenopus oocyte pairs shows that Shaking B proteins are functional components of gap junctions. We have called this family of gap- junction proteins the innexins. The shaking B locus encodes three members of the innexin family: Shaking B (neural), Shaking B (n+16) and Shaking B (lethal). Targeted expression show that Shaking B (n+16) expression presynaptically in the GF and Shaking B (lethal) postsynaptically in the TTMn is required for electrical synapse formation between these neurons. In vitro expression of ShakB (n+16) and ShakB (lethal) in neighbouring Xenopus oocytes results in the formation of heterotypic intercellular channels which are asymmetrically gated by transjunctional voltage and exhibit classical rectification. These data show that rectification is achieved by differential regulation of the pre- and post-synaptic elements of structurally asymmetric junctions. In vertebrates, gap-junction channels were thought to be entirely composed of a different protein family, called connexins, but recent work (not at Sussex) has shown that functional innexin-like proteins, termed pannexins, are also expressed in vertebrates. The simple diploblastic organism Hydra appears to possess only innexins - so we conclude that innexins are the primordial gap-junction molecules, while connexins evolved more recently in the deuterostomes.



Jonathan Bacon is Professor of Neuroscience in the School of Life Sciences, University of Sussex, UK, and is Adjunct Professor of Neuroscience in the Department of Neuroscience, University of Arizona, Tucson. His first degree was at Cambridge. After a year teaching in Jamaica, he took an MSc and a PhD at Manchester, and postdocs in: Seewiesen, Germany; Albany, USA; Basel, Switzerland. He joined the faculty in Biology at the University of Sussex in 1984, where he was awarded the 1987 President’s Medal of the Society for Experimental Biology, and was the Dean of Life Sciences from 2002-2009. His research examines: insect behaviour and its underlying neural circuitry; gap-junctional (innexin-mediated) cell-cell communication; foraging behaviour of Pharaoh's ants and honey bees.

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