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06:45
Transmembrane Domain Oligomerization Propensity determined by ToxR Assay
Published on: May 26, 2011
Multifunctional basic motif in the glycine receptor intracellular domain induces subunit-specific sorting
Nima Melzer1, Carmen Villmann1, Kristina Becker1
1From the Institut für Biochemie (Emil-Fischer-Zentrum), Universität Erlangen-Nürnberg, Erlangen 91054, Germany.
The Journal of Biological Chemistry
|December 5, 2009
Summary
The glycine receptor (GlyR) TM3-4 loop
Area of Science:
- Neuroscience
- Molecular Biology
- Cell Biology
Background:
- The strychnine-sensitive glycine receptor (GlyR) is a Cys-loop receptor crucial for fast synaptic inhibition in the vertebrate central nervous system.
- GlyRs assemble from five homologous subunits, each possessing distinct structural domains, including transmembrane (TM) domains and intracellular loops.
Purpose of the Study:
- To investigate the intracellular trafficking capabilities of GlyR subunits.
- To identify the specific structural motifs responsible for nuclear localization signals within GlyR subunits.
Main Methods:
- Live cell imaging of green fluorescent protein and beta-galactosidase-tagged GlyR domain constructs.
- Yeast two-hybrid screening and GST pulldown assays to identify interacting proteins.
Main Results:
- The TM3-4 loops of GlyRalpha1 and GlyRalpha3 subunits, but not GlyRalpha2 or -beta, demonstrated nuclear sorting activity.
- A conserved basic motif within the TM3-4 loop was identified as a key determinant for nuclear localization.
- Karyopherin alpha3 and alpha4 were found to interact with the GlyR TM3-4 loop, mediating intracellular trafficking.
Conclusions:
- The TM3-4 loop's basic motif acts as a multifunctional element, directing karyopherin-dependent intracellular sorting of full-length GlyRs.
- Subunit-specific differences in nuclear localization are likely due to minor amino acid variations in the basic motif.
- This study elucidates a novel mechanism for GlyR intracellular transport and localization.
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