Two alanines juxtaposed to aggrecan's G1 domain alter its intracellular localization
Article first published online: 17 SEP 2003
Copyright © 2003 Wiley-Liss, Inc.
Journal of Cellular Biochemistry
Volume 90, Issue 3, pages 592–607, 15 October 2003
How to Cite
Oliver, B. L., Cronin, C. G., Bue, C., Hand, A. R. and Tanzer, M. L. (2003), Two alanines juxtaposed to aggrecan's G1 domain alter its intracellular localization. J. Cell. Biochem., 90: 592–607. doi: 10.1002/jcb.10651
- Issue published online: 26 SEP 2003
- Article first published online: 17 SEP 2003
- Manuscript Accepted: 18 JUL 2003
- Manuscript Received: 2 MAY 2003
- National Institutes of Health (to M.L.T.). Grant Number: R01-AR45909
- endoplasmic reticulum;
- intracellular trafficking;
- ER accumulations
Nascent proteins translated and processed in the endoplasmic reticulum (ER) sometimes contain intrinsic signals for ER retention or ER retrieval. These signals are usually a few amino acids in length, and if alanine modifications are made within these sequences, normal transit patterns of the nascent protein frequently change. The purpose of this study was to determine whether two alanines juxtaposed to the first globular domain of aggrecan's core protein affect its transit in Chinese hamster ovary (CHO) cells. Results show that two alanines juxtaposed to the first globular domain (G1AA) minimized secretion of the protein. However, transgenic proteins with juxtaposed glutamate–phenylalanine (G1EF) or no additional amino acids (G1) were still secreted. GFP-tagged G1AA localized in the lumen of the ER but not in the Golgi. In contrast, a portion of GFP-tagged G1EF and G1 did appear in the Golgi compartment. More importantly, unique and striking accumulations of G1EF and G1 transgenic proteins were seen in large dilated regions of the ER cisternae, reminiscent of accumulations seen in α1-antitrypsin deficiency disease. G1AA transgenic proteins did not form these vesicles but were diffusely distributed throughout the ER lumen. These results indicate that just two juxtaposed alanines can profoundly affect a large globular protein's intracellular localization. © 2003 Wiley-Liss, Inc.