Subdomain-specific localization of CLIMP-63 (p63) in the endoplasmic reticulum is mediated by its luminal alpha-helical segment

Klopfenstein, D. R. and Klumperman, J. and Lustig, A. and Kammerer, R. A. and Oorschot, V. and Hauri, H. P.. (2001) Subdomain-specific localization of CLIMP-63 (p63) in the endoplasmic reticulum is mediated by its luminal alpha-helical segment. The Journal of cell biology, Vol. 153, H. 6. pp. 1287-1300.

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Official URL: http://edoc.unibas.ch/dok/A5257763

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The microtubule-binding integral 63 kD cytoskeleton-linking membrane protein (CLIMP-63; former name, p63) of the rough endoplasmic reticulum (ER) is excluded from the nuclear envelope. We studied the mechanism underlying this ER subdomain-specific localization by mutagenesis and structural analysis. Deleting the luminal but not cytosolic segment of CLIMP-63 abrogated subdomain-specific localization, as visualized by confocal microscopy in living cells and by immunoelectron microscopy using ultrathin cryosections. Photobleaching/recovery analysis revealed that the luminal segment determines restricted diffusion and immobility of the protein. The recombinant full-length luminal segment of CLIMP-63 formed alpha-helical 91-nm long rod-like structures as evident by circular dichroism spectroscopy and electron microscopy. In the analytical ultracentrifuge, the luminal segment sedimented at 25.7 S, indicating large complexes. The complexes most likely arose by electrostatic interactions of individual highly charged coiled coils. The findings indicate that the luminal segment of CLIMP-63 is necessary and sufficient for oligomerization into alpha-helical complexes that prevent nuclear envelope localization. Concentration of CLIMP-63 into patches may enhance microtubule binding on the cytosolic side and contribute to ER morphology by the formation of a protein scaffold in the lumen of the ER.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Former Organization Units Biozentrum > Pharmacology/Neurobiology (Hauri)
UniBasel Contributors:Hauri, Hans-Peter
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Rockefeller University Press
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:31 Dec 2015 10:42
Deposited On:22 Mar 2012 13:18

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