期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 102, 期 35, 页码 12595-12600出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0503253102
关键词
ligand-gated ion channel; receptor structure
资金
- Biotechnology and Biological Sciences Research Council [B19797] Funding Source: Medline
- Wellcome Trust Funding Source: Medline
- Biotechnology and Biological Sciences Research Council [B19797] Funding Source: researchfish
The 5-HT3 receptor is a cation-selective ligand-gated ion channel of the Cys-loop superfamily. The receptor is an important therapeutic target, with receptor antagonists being widely used as antiemetics in cancer therapy. The two known receptor subunits, A and B, form homomeric 5-HT3A receptors and heteromeric 5-HT3A/B receptors. The heteromeric receptor has the higher single-channel conductance and more closely mimics the properties of the native receptor. We have used atomic force microscopy to study the architecture of 5-HT3A and 5-HT3A/B receptors. We engineered different epitope tags onto the A- and B-subunits and imaged receptors that were doubly liganded by anti-epitope antibodies. We found that, for the 5-HT3A/B receptor, the distribution of angles between antibodies against the A-subunit had a single peak at approximate to 144 degrees, whereas the distribution for antibodies against the B-subunit had two peaks at approximate to 72 degrees and 144 degrees. Our results indicate that the subunit stoichionnetry is 2A:3B and that the subunit arrangement around the receptor rosette is B-B-A-B-A. This arrangement may account for the difference between the agonist Hill coefficients and the single-channel conductances for the two types of receptor.
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