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A modified dileucine motif mediates the internalization of a G‐protein activated inward potassium channel
Author(s) -
Rangel Claudia Iveth,
DíazBello Beatriz,
Padilla Teresa,
López Zinaeli,
Salvador Carolina,
Escobar Laura
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.lb602
Subject(s) - g protein coupled inwardly rectifying potassium channel , internalization , xenopus , microbiology and biotechnology , potassium channel , biology , phosphorylation , alanine scanning , mutant , ion channel , biophysics , g protein , biochemistry , receptor , mutagenesis , signal transduction , gene
G‐protein‐activated inward rectifying potassium channels (GIRK) participate in inhibitory synapsis, where neurotransmitters activate Gi/Go protein coupled receptors. Gβγ dimers bind and open GIRK channels, hyperpolaryzing the postsynaptic membrane. GIRK (GIRK1‐4) subunits form heteromultimers of GIRK1 in mammals. GIRK5 channels are expressed in Xenopus laevis oocytes. We previously found that phosphorylation of a tyrosine (Y16) at the NH 2 ‐terminal of GIRK5, keeps the channels internalized (Mora and Escobar, 2005). The sequence E 17 XXXLI 22 , reported as an internalization and/or a lysosomal targeting motif, is localized upstream of Y16. Therefore, we aim to explore the role of this dileucine motif in the GIRK5 functional expression in oocytes. We performed alanine scanning mutagenesis and whole cell voltage‐clamp recordings. The single mutants L15A, E17A, S18A, P19A, Q20A, L21A and Q23A did not produce inwardly rectifying currents. In contrast, Y16A, I22A and the quadruple mutant Y16A/E17A/L21A/I22A displayed inward current amplitudes according to the number of mutant residues. In conclusion, our results suggest that the sequence Y 16 I 22 at the NH 2 ‐term of GIRK5 determines the internalization of the GIRK5 channels in Xenopus laevis oocytes.