title: Role of the C-terminal di-leucine motif of 5-HT1A and 5-HT1B serotonin receptors in plasma membrane targeting.
abstract: The 5-HT1A and 5-HT1B serotonin receptors exhibit different subcellular localizations in neurons. Evidence has been reported that the C-terminal domain is involved in the somato-dendritic and axonal targeting of 5-HT1AR and 5-HT1BR, respectively. Here we analyzed the consequences of the mutation of a di-leucine motif and palmitoylated cysteines within this domain. Replacement of I414-I415 by a di-alanine in 5-HT1AR led to endoplasmic reticulum (ER) sequestration of the corresponding mutant expressed in cell lines as well as in hippocampal neurons in culture. Furthermore, di-leucine-mutated receptors were unable to bind 5-HT1A agonists and presented a major deficit in their glycosylation state, suggesting that they are misfolded. By contrast, mutation of the di-leucine motif in the C-terminal domain of 5-HT1BR had no major consequence on its subcellular targeting. However, in the case of the 1ActB chimera (substitution of the C-terminal domain of the 5-HT1BR into 5-HT1AR), this mutation was also found to cause sequestration within the ER. Replacement of palmitoylated cysteines by serines had no consequence on either receptor type. These data indicate that the di-leucine motif of the 5-HT1AR and 5-HT1BR tails is implicated in proper folding of these receptors, which is necessary for their ER export.
authors.affiliation: INSERM, U677, University Pierre et Marie Curie, Paris 75013, France.
authors.forename: Damien
authors.initials: D
authors.lastname: Carrel
authors.forename: Michel
authors.initials: M
authors.lastname: Hamon
authors.forename: Michèle
authors.initials: M
authors.lastname: Darmon
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D019556:COS Cells; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D003545:Cysteine / Q000235:genetics / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect / Q000379:methods; D007930:Leucine / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D011485:Protein Binding; D021381:Protein Transport / Q000187:drug effects; D044282:Receptor, Serotonin, 5-HT1A / Q000235:genetics / Q000378:metabolism*; D044302:Receptor, Serotonin, 5-HT1B / Q000235:genetics / Q000378:metabolism*; D058825:Serotonin 5-HT1 Receptor Agonists; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D013552:Swine
chemical_list: D044302:Receptor, Serotonin, 5-HT1B; D058825:Serotonin 5-HT1 Receptor Agonists; D017366:Serotonin Receptor Agonists; D044282:Receptor, Serotonin, 5-HT1A; D007930:Leucine; D003545:Cysteine