Cell surface expression of 5-hydroxytryptamine type 3 receptors is controlled by an endoplasmic reticulum retention signal

Gary W. Boyd, Anne I. Doward, Ewen F. Kirkness, Neil S. Millar, Christopher N. Connolly

    Research output: Contribution to journalArticle

    43 Citations (Scopus)

    Abstract

    Two subunits of the 5-hydroxytryptamine type 3 (5-HT3) have been identified (5-HT3A and 5-HT3B) that assemble into homomeric (5-HT3A) and heteromeric (5-HT3A + 5-HT3B) complexes. Unassembled 5-HT3B subunits are efficiently retained within the cell. In this study, we address the mechanism controlling the release of 5-HT3B from the endoplasmic reticulum (ER). An analysis of chimeric 5-HT3A receptor(R).5-HT3BR constructs suggests the presence of elements downstream of the first transmembrane domain of 5-HT3B subunits that inhibit cell surface expression. To investigate this possibility, truncated 5-HT3B subunits were constructed and assessed for their ability to access the cell surface in COS-7 and ts201 cells. Using this approach, we have identified the presence of an ER retention signal located within the first cytoplasmic loop between transmembrane domains I and II of 5-HT3B. Transplantation of this signal (CRAR) into the homologous region of 5-HT3A results in the ER retention of this subunit until rescued by co-assembly with wild-type 5-HT3A. The mutation of this ER retention signal in 5-HT3B (5-HT(3B)SGER) does not lead to cell surface expression, suggesting the presence of other signals or mechanisms to control the surface expression of 5-HT(3B)Rs. The generation of truncated 5-HT(3B)SGER constructs confirmed that the CRAR signal does play an important role in the ER retention of 5-HT3B.

    Original languageEnglish
    Pages (from-to)27681-27687
    Number of pages7
    JournalJournal of Biological Chemistry
    Volume278
    Issue number30
    DOIs
    Publication statusPublished - 25 Jul 2003

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