Subcellular localization and endocytosis of homomeric γ2 subunit splice variants of γ-aminobutyric acid type A receptors

Christopher N. Connolly, Julia M. Uren, Phillip Thomas, George H. Gorrie, Adele Gibson, Trevor G. Smart, Stephen J. Moss

    Research output: Contribution to journalArticle

    67 Citations (Scopus)

    Abstract

    The expression of a and ß ?-aminobutyric acid type A receptor subunits produces GABA-gated channels which require the incorporation of either the ?2 or ?3 subunit for benzodiazepine modulation. Here we examine the role of the ?2 subunit splice variants, ?2S and ?2L which differ by eight amino acids
    in the major intracellular domain, in mediating cell surface expression. Using immunocytochemistry we have demonstrated that when expressed alone, the ?2S subunit can access the cell surface and internalize constitutively. In contrast, a1, ß2and ?2L are retained predominantly in the endoplasmic reticulum (ER)
    when expressed alone. Replacing the insert which differentiates ?2L from
    ?2S (LLRMFSFK) with eight alanines produces a phenotype identical to ?2S. Both ?2 subunits fail to produce high molecular weight oligomers observed for a1ß2 and a1ß2?2 heterooligomers and do not form functional ion channels. Surface
    expression of ?2S is repressed upon the coexpression of a1 or ß2 subunits, resulting in ER-retained heterooligomers, suggesting that homomeric
    ?2S is unlikely to occur in vivo. However, its independent maturation
    to surface competence and preferential assembly with a and ß subunits may ensure the production of functional benzodiazepine-sensitive receptors. Furthermore, the presence of the ?2 subunit appears to confer an endocytotic capacity to these heterooligomeric receptors.

    Original languageEnglish
    Pages (from-to)259-271
    Number of pages13
    JournalMolecular and Cellular Neuroscience
    Volume13
    Issue number4
    DOIs
    Publication statusPublished - 1999

    Cite this

    Connolly, Christopher N. ; Uren, Julia M. ; Thomas, Phillip ; Gorrie, George H. ; Gibson, Adele ; Smart, Trevor G. ; Moss, Stephen J. / Subcellular localization and endocytosis of homomeric γ2 subunit splice variants of γ-aminobutyric acid type A receptors. In: Molecular and Cellular Neuroscience. 1999 ; Vol. 13, No. 4. pp. 259-271.
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    abstract = "The expression of a and {\ss} ?-aminobutyric acid type A receptor subunits produces GABA-gated channels which require the incorporation of either the ?2 or ?3 subunit for benzodiazepine modulation. Here we examine the role of the ?2 subunit splice variants, ?2S and ?2L which differ by eight amino acids in the major intracellular domain, in mediating cell surface expression. Using immunocytochemistry we have demonstrated that when expressed alone, the ?2S subunit can access the cell surface and internalize constitutively. In contrast, a1, {\ss}2and ?2L are retained predominantly in the endoplasmic reticulum (ER) when expressed alone. Replacing the insert which differentiates ?2L from ?2S (LLRMFSFK) with eight alanines produces a phenotype identical to ?2S. Both ?2 subunits fail to produce high molecular weight oligomers observed for a1{\ss}2 and a1{\ss}2?2 heterooligomers and do not form functional ion channels. Surface expression of ?2S is repressed upon the coexpression of a1 or {\ss}2 subunits, resulting in ER-retained heterooligomers, suggesting that homomeric ?2S is unlikely to occur in vivo. However, its independent maturation to surface competence and preferential assembly with a and {\ss} subunits may ensure the production of functional benzodiazepine-sensitive receptors. Furthermore, the presence of the ?2 subunit appears to confer an endocytotic capacity to these heterooligomeric receptors.",
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    Subcellular localization and endocytosis of homomeric γ2 subunit splice variants of γ-aminobutyric acid type A receptors. / Connolly, Christopher N.; Uren, Julia M.; Thomas, Phillip; Gorrie, George H.; Gibson, Adele; Smart, Trevor G.; Moss, Stephen J.

    In: Molecular and Cellular Neuroscience, Vol. 13, No. 4, 1999, p. 259-271.

    Research output: Contribution to journalArticle

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    T1 - Subcellular localization and endocytosis of homomeric γ2 subunit splice variants of γ-aminobutyric acid type A receptors

    AU - Connolly, Christopher N.

    AU - Uren, Julia M.

    AU - Thomas, Phillip

    AU - Gorrie, George H.

    AU - Gibson, Adele

    AU - Smart, Trevor G.

    AU - Moss, Stephen J.

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    AB - The expression of a and ß ?-aminobutyric acid type A receptor subunits produces GABA-gated channels which require the incorporation of either the ?2 or ?3 subunit for benzodiazepine modulation. Here we examine the role of the ?2 subunit splice variants, ?2S and ?2L which differ by eight amino acids in the major intracellular domain, in mediating cell surface expression. Using immunocytochemistry we have demonstrated that when expressed alone, the ?2S subunit can access the cell surface and internalize constitutively. In contrast, a1, ß2and ?2L are retained predominantly in the endoplasmic reticulum (ER) when expressed alone. Replacing the insert which differentiates ?2L from ?2S (LLRMFSFK) with eight alanines produces a phenotype identical to ?2S. Both ?2 subunits fail to produce high molecular weight oligomers observed for a1ß2 and a1ß2?2 heterooligomers and do not form functional ion channels. Surface expression of ?2S is repressed upon the coexpression of a1 or ß2 subunits, resulting in ER-retained heterooligomers, suggesting that homomeric ?2S is unlikely to occur in vivo. However, its independent maturation to surface competence and preferential assembly with a and ß subunits may ensure the production of functional benzodiazepine-sensitive receptors. Furthermore, the presence of the ?2 subunit appears to confer an endocytotic capacity to these heterooligomeric receptors.

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