| First Author | Korkhov VM | Year | 2008 |
| Journal | J Mol Biol | Volume | 378 |
| Issue | 2 | Pages | 337-52 |
| PubMed ID | 18367207 | Mgi Jnum | J:170801 |
| Mgi Id | MGI:4947360 | Doi | 10.1016/j.jmb.2008.02.056 |
| Citation | Korkhov VM, et al. (2008) Peptide-based interactions with calnexin target misassembled membrane proteins into endoplasmic reticulum-derived multilamellar bodies. J Mol Biol 378(2):337-52 |
| abstractText | Oligomeric assembly of neurotransmitter transporters is a prerequisite for their export from the endoplasmic reticulum (ER) and their subsequent delivery to the neuronal synapse. We previously identified mutations, e.g., in the gamma-aminobutyric acid (GABA) transporter-1 (GAT1), which disrupted assembly and caused retention of the transporter in the ER. Using one representative mutant, GAT1-E101D, we showed here that ER retention was due to association of the transporter with the ER chaperone calnexin: interaction with calnexin led to accumulation of GAT1 in concentric bodies corresponding to previously described multilamellar ER-derived structures. The transmembrane domain of calnexin was necessary and sufficient to direct the protein into these concentric bodies. Both yellow fluorescent protein-tagged versions of wild-type GAT1 and of the GAT1-E101D mutant remained in disperse (i.e., non-aggregated) form in these concentric bodies, because fluorescence recovered rapidly (t(1/2) approximately 500 ms) upon photobleaching. Fluorescence energy resonance transfer microscopy was employed to visualize a tight interaction of GAT1-E101D with calnexin. Recognition by calnexin occurred largely in a glycan-independent manner and, at least in part, at the level of the transmembrane domain. Our findings are consistent with a model in which the transmembrane segment of calnexin participates in chaperoning the inter- and intramolecular arrangement of hydrophobic segment in oligomeric proteins. |
