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Cryo-EM structure of human Cx31.3/GJC3 connexin hemichannel.


ABSTRACT: Connexin family proteins assemble into hexameric channels called hemichannels/connexons, which function as transmembrane channels or dock together to form gap junction intercellular channels (GJIChs). We determined the cryo-electron microscopy structures of human connexin 31.3 (Cx31.3)/GJC3 hemichannels in the presence and absence of calcium ions and with a hearing-loss mutation R15G at 2.3-, 2.5-, and 2.6-Å resolutions, respectively. Compared with available structures of GJICh in open conformation, Cx31.3 hemichannel shows substantial structural changes of highly conserved regions in the connexin family, including opening of calcium ion-binding tunnels, reorganization of salt-bridge networks, exposure of lipid-binding sites, and collocation of amino-terminal helices at the cytoplasmic entrance. We also found that the hemichannel has a pore with a diameter of ~8 Å and selectively transports chloride ions. Our study provides structural insights into the permeant selectivity of Cx31.3 hemichannel.

SUBMITTER: Lee HJ 

PROVIDER: S-EPMC7455182 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature

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Cryo-EM structure of human Cx31.3/GJC3 connexin hemichannel.

Lee Hyuk-Joon HJ   Jeong Hyeongseop H   Hyun Jaekyung J   Ryu Bumhan B   Park Kunwoong K   Lim Hyun-Ho HH   Yoo Jejoong J   Woo Jae-Sung JS  

Science advances 20200828 35


Connexin family proteins assemble into hexameric channels called hemichannels/connexons, which function as transmembrane channels or dock together to form gap junction intercellular channels (GJIChs). We determined the cryo-electron microscopy structures of human connexin 31.3 (Cx31.3)/GJC3 hemichannels in the presence and absence of calcium ions and with a hearing-loss mutation R15G at 2.3-, 2.5-, and 2.6-Å resolutions, respectively. Compared with available structures of GJICh in open conformat  ...[more]

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