Skip Navigation

This Article
Right arrow Full Text Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (3)
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Iwama, H.
Right arrow Articles by Gojobori, T.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Iwama, H.
Right arrow Articles by Gojobori, T.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Molecular Biology and Evolution 19:1891-1901 (2002)
© 2002 Society for Molecular Biology and Evolution

Identification of Neurotransmitter Receptor Genes Under Significantly Relaxed Selective Constraint by Orthologous Gene Comparisons Between Humans and Rodents

Hisakazu Iwama and Takashi Gojobori

Center for Information Biology and DNA Data Bank of Japan, National Institute of Genetics, Mishima-shi

Neurotransmitter receptors (neuroreceptors) are classified into two types, G protein–coupled receptors (GPCRs) and ligand-gated ion channels. The former occupies a small part of the large GPCR superfamily, whereas the latter consists of three superfamilies. In these superfamilies, humans and rodents share almost the same set of neuroreceptor genes. This neuroreceptor gene set is good material to examine the degree of selective constraint exerted on each member gene of a given superfamily. If there are any neuroreceptor genes under the degree of selective constraint that is very different from that of the other member genes, they may have influenced the functional features characteristic of human neural activities. With the aim of identifying such neuroreceptor genes, we collected sequence data of orthologous neuroreceptor genes for humans, mice, and rats by database searches. This data set included ortholog pairs for 141 kinds of neuroreceptor genes, which covered almost the whole set of neuroreceptor genes known to be expressed in the human brain. The degree of selective constraint was estimated by computing the ratio (dN/dS) of the number of nonsynonymous substitutions to that of synonymous substitutions. We found that the dN/dS ratio ranged widely and its distribution fitted a gamma distribution. In particular, we found that four neuroreceptor genes are under the significantly relaxed selective constraint. They are an ionotropic glutamate receptor subunit NMDA-2C, two GABAA receptor subunits, i.e., GABAA-{epsilon} and GABAA-{theta}, and a dopamine receptor D4. Interestingly, these neuroreceptors have been reported to be associated with cognitive abilities such as memory and learning, and responsiveness to novel stimuli. These cognitive abilities can influence the behavioral features of an individual. Thus, it suggests that the relaxed-constraint neuroreceptor genes have evolved, assuring that the nervous system responds to a variety of stimuli with proper flexibility.


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 Mol Biol EvolHome page
A. M. Andres, C. de Hemptinne, and J. Bertranpetit
Heterogeneous Rate of Protein Evolution in Serotonin Genes
Mol. Biol. Evol., December 1, 2007; 24(12): 2707 - 2715.
[Abstract] [Full Text] [PDF]

Home page
 GeneticsHome page
M. Xiong, J. Li, and X. Fang
Identification of Genetic Networks
Genetics, February 1, 2004; 166(2): 1037 - 1052.
[Abstract] [Full Text] [PDF]


Disclaimer:
Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.