期刊
EMBO JOURNAL
卷 21, 期 14, 页码 3598-3607出版社
WILEY
DOI: 10.1093/emboj/cdf365
关键词
calcium; connexon; intercellular communication; ion channel structure; membrane protein structure
资金
- NCRR NIH HHS [RR04050, P41 RR004050] Funding Source: Medline
- NIGMS NIH HHS [R01 GM065937] Funding Source: Medline
Gap junction channels mediate communication between adjacent cells. Using atomic force microscopy (AFM), we have imaged conformational changes of the cytoplasmic and extracellular surfaces of native connexin 26 gap junction plaques. The cytoplasmic domains of the gap junction surface, imaged at submolecular resolution, form a hexameric pore protruding from the membrane bilayer. Exhibiting an intrinsic flexibility, these cytoplasmic domains, comprising the C-terminal connexin end, reversibly collapse by increasing the forces applied to the AFM stylus. The extracellular connexon surface was imaged after dissection of the gap junction with the AFM stylus. Upon injection of Ca2+ into the buffer solution, the extracellular channel entrance reduced its diameter from 1.5 to 0.6 nm, a conformational change that is fully reversible and specific among the divalent cations tested. Ca2+ had a profound effect on the cytoplasmic surface also, inducing the formation of microdomains. Consequently, the plaque height increased by 0.6 nm to 18 nm. This suggests that calcium ions induce conformational changes affecting the structure of both the hemichannels and the intact channels forming cell-cell contacts.
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