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Endosomal trafficking of the Menkes copper ATPase ATP7A is mediated by vesicles containing the Rab7 and Rab5 GTPase proteins

journal contribution
posted on 2003-12-10, 00:00 authored by M Pascale, S Franceschelli, O Moltedo, F Belleudi, M Torrisi, C Bucci, Sharon La FontaineSharon La Fontaine, Julian MercerJulian Mercer, A Leone
The Cu-ATPase ATP7A (MNK) is localized in the trans-Golgi network (TGN) and relocalizes in the plasma membrane via vesicle-mediated traffic following exposure of the cells to high concentrations of copper. Rab proteins are organelle-specific GTPases, markers of different endosomal compartments; their role has been recently reviewed (Trends Cell Biol. 11(2001) 487). In this article we analyze the endosomal pathway of trafficking of the MNK protein in stably transfected clones of CHO cells, expressing chimeric Rab5-myc or Rab7-myc proteins, markers of early or late endosome compartments, respectively. We demonstrate by immunofluorescence and confocal and electron microscopy techniques that the increase in the concentration of copper in the medium (189 μM) rapidly induces a redistribution of the MNK protein from early sorting endosomes, positive for Rab5-myc protein, to late endosomes, containing the Rab7-myc protein. Cell fractionation experiments confirm these results; i.e., the MNK protein is recruited to the endosomal fraction on copper stimulation and colocalizes with Rab5 and Rab7 proteins. These findings allow the first characterization of the vesicles involved in the intracellular routing of the MNK protein from the TGN to the plasma membrane, a key mechanism allowing appropriate efflux of copper in cells grown in high concentrations of the metal.


History

Journal

Experimental cell research

Volume

291

Issue

2

Pagination

377 - 385

Publisher

Academic Press

Location

San Diego, Calif

ISSN

0014-4827

eISSN

1090-2422

Language

eng

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2003, Elsevier Inc.