Human 5-HT3B -- Arg 268

Species Original Mutated to Mutation
Human Arg 268 Gly


Rat Equivalent Arg 264    
Mouse Equivalent Arg 264  





The wild type 5-HT3B receptor is retained within the endoplasmic reticulum. In this study, the 5-HT3B subunit was cleaved at various positions, beginning from the C-terminus, to determine which residues were responsible for the intracellular retention. Truncation downstream of the first transmembrane domain resulted in 5-HT3B surface expression. The 5-HT3B first cytoplasmic domain differs from the homologous region of the 5-HT3A subunit by four amino acids, and so those four amino acids native to the 5-HT3A subunit (ser-gly-glu-arg) were transplanted into the 5-HT3B subunit in place of its native residues (cys-arg-ala-arg). Even with the SGER motif, the 5-HT3B mutant receptor was still retained within the cell, suggesting that other regions of the amino acid sequence are also responsible for an ER retention signal within 5-HT3B. This led to cleaving the mutant 5-HT3B subunit at various positions downstream of the mutation to determine what other regions may be necessary for intracellular retention/cell surface expression.


Boyd GW, Doward AI, Kirkness EF, Millar NS, Connolly CN. (2003) Cell surface expression of 5-hydroxytryptamine type 3 receptors is controlled by an endoplasmic reticulum retention signal. The Journal of Biological Chemistry . 278(30):27681-7

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