Abstract
The gene and cDNAs that encode a novel subunit of rodent serotonin 5-HT(3) receptors were isolated from mouse and rat tissues. Each of the new rodent subunits shares 40% amino acid identity with the rat 5-HT(3A) subunit and 73% identity with the human 5-HT(3B) subunit. Despite a relatively low level of structural conservation, sequence analysis and functional studies suggest that the new rodent subunits are orthologues of the human 5-HT(3B) subunit. In common with homologous human receptors, rat heteromeric 5-HT(3) receptors displayed a substantially larger single-channel conductance than homomeric 5-HT(3A) receptors. In addition, the rat heteromeric receptors were less sensitive to antagonism by tubocurarine. However, in contrast to human heteromeric receptors, those of the rat displayed pronounced inward rectification of both the whole-cell and single-channel current amplitudes. Transcripts of the mouse 5-HT(3A) and 5-HT(3B) subunits are coexpressed in several cell lines that possess endogenous 5-HT(3) receptors. In addition, treatment of rat PC12 cells with nerve growth factor induced expression of both subunit mRNAs, with a similar time course for accumulation of each transcript. The combination of functional data and expression patterns is consistent with the existence of heteromeric 5-HT(3) receptors in rodent neurons.
Original language | English |
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Pages (from-to) | 240-7 |
Number of pages | 8 |
Journal | Journal of Neurochemistry |
Volume | 75 |
Issue number | 1 |
DOIs | |
Publication status | Published - Jul 2000 |
Keywords
- Amino Acid Sequence
- Animals
- Cloning, Molecular
- DNA, Complementary
- Electric Conductivity
- Gene Expression
- Humans
- Macromolecular Substances
- Mice
- Molecular Sequence Data
- PC12 Cells
- RNA, Messenger/analysis
- Rats
- Receptors, Serotonin/chemistry
- Receptors, Serotonin, 5-HT3
- Recombinant Proteins/metabolism
- Sequence Homology