TY - JOUR
T1 - A Single Lys Residue on the First Intracellular Loop Modulates the Endoplasmic Reticulum Export and Cell-Surface Expression of α2A-Adrenergic Receptor
AU - Fan, Yi
AU - Li, Chunman
AU - Guo, Jianhui
AU - Hu, Gang
AU - Wu, Guangyu
PY - 2012/12/5
Y1 - 2012/12/5
N2 - Export from the endoplasmic reticulum (ER) represents an initial step in intracellular trafficking of G protein-coupled receptors (GPCRs). However, the underlying molecular mechanisms remain poorly understood. We have previously demonstrated that a highly conserved Leu residue on the first intracellular loop (ICL1) is required for exit of several GPCRs from the ER. Here we found that, in addition to Leu64 residue in the ICL1, the neighboring positively charged residue Lys65also modulates the cell-surface transport of α2A-adrenergic receptor (α2A-AR). Mutation of Lys65 to Ala, Glu and Gln significantly attenuated, whereas mutation of Lys65 to Arg strongly augmented α2A-AR expression at the cell surface. Consistent with the effects on the cell-surface expression of α2A-AR, mutation of Lys65 to Ala and Arg produced opposing effects on α2A-AR-mediated ERK1/2 activation. Furthermore, confocal microscopy revealed that the α2A-AR mutant K65A displayed a strong intracellular expression pattern and was extensively co-localized with the ER marker DsRed2-ER, suggestive of ER accumulation. These data provide the first evidence indicating an important function for a single Lys residue on the ICL1 in the ER export and cell-surface expression of α2A-AR. These data also suggest that the ICL1 may possess multiple signals that control the cell-surface targeting of GPCRs via distinct mechanisms.
AB - Export from the endoplasmic reticulum (ER) represents an initial step in intracellular trafficking of G protein-coupled receptors (GPCRs). However, the underlying molecular mechanisms remain poorly understood. We have previously demonstrated that a highly conserved Leu residue on the first intracellular loop (ICL1) is required for exit of several GPCRs from the ER. Here we found that, in addition to Leu64 residue in the ICL1, the neighboring positively charged residue Lys65also modulates the cell-surface transport of α2A-adrenergic receptor (α2A-AR). Mutation of Lys65 to Ala, Glu and Gln significantly attenuated, whereas mutation of Lys65 to Arg strongly augmented α2A-AR expression at the cell surface. Consistent with the effects on the cell-surface expression of α2A-AR, mutation of Lys65 to Ala and Arg produced opposing effects on α2A-AR-mediated ERK1/2 activation. Furthermore, confocal microscopy revealed that the α2A-AR mutant K65A displayed a strong intracellular expression pattern and was extensively co-localized with the ER marker DsRed2-ER, suggestive of ER accumulation. These data provide the first evidence indicating an important function for a single Lys residue on the ICL1 in the ER export and cell-surface expression of α2A-AR. These data also suggest that the ICL1 may possess multiple signals that control the cell-surface targeting of GPCRs via distinct mechanisms.
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U2 - 10.1371/journal.pone.0050416
DO - 10.1371/journal.pone.0050416
M3 - Article
C2 - 23227171
AN - SCOPUS:84870814078
SN - 1932-6203
VL - 7
JO - PLoS One
JF - PLoS One
IS - 12
M1 - e50416
ER -