5-Hydroxytryptamine receptor subtypes in vertebrates and invertebrates.
In the last few years, molecular biology has led to the cloning and characterization of several 5-HT receptors (serotonin receptors) in vertebrates and in invertebrates. These studies have allowed identification not only of 5-HT receptors already described but also of novel subtypes. The molecular cloning of 13 different mammalian receptor subtypes revealed an unexpected heterogeneity among 5-HT receptors. Except for the 5-HT3 receptors which are ligand-gated ion channel receptors, all the other 5-HT receptors belong to the large family of receptors interacting with G proteins. Based on their amino acid sequence homology and coupling to second messengers these receptors can be divided into distinct families: the 5-HT1 family contains receptors that are negatively coupled to adenylate cyclase: the 5-HT2 family includes receptors that stimulate phospholipase C; the adenylyl cyclase stimulatory receptors are a heterogeneous group including the 5-HT4 receptor which has not yet been cloned, the Drosophila 5-HTdro1 receptor and two mammalian receptors tentatively named 5-HT6 and 5-HT7 receptors. The 5-HT5A and 5-HT5B receptors might constitute a new family of 5-HT receptors whose effectors are unknown. This review focusses on the molecular characteristics of the cloned 5-HT receptors such as their structure, their effector systems and their distribution within the central nervous system. The existence of a large number of receptors with distinct signalling properties and expression patterns might enable a single substance like 5-HT to generate simultaneously a large panel of effects in many brain structures. The availability of the genes encoding these receptors has already allowed a partial characterization of their structure-function relationship and will probably allow in the future a dissection of the contribution of each of these receptor subtypes to physiology and behaviour.
Saudou
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Laboratoire de Génétique Moléculaire des Eucaryotes du CNRS, Unité 184 de l'INSERM, Faculté de Médecine, Strasbourg, France.
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D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000378:metabolism; D000262:Adenylyl Cyclases / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D006224:Cricetinae; D004330:Drosophila / Q000378:metabolism; D006801:Humans; D007448:Invertebrates / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D051381:Rats; D011985:Receptors, Serotonin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism*; D014714:Vertebrates / Q000378:metabolism*
D011985:Receptors, Serotonin; D012701:Serotonin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D000262:Adenylyl Cyclases