Members of the p24 family of putative cargo receptors (subdivided into p24-α, −β, −γ and −δ) are localized in the intermediate-and cis-Golgi compartments of the early secretory pathway, and are thought to play an important role in protein transport. In the present study, we wondered what effect increased biosynthetic cell activity with resulting high levels of protein transport would have on the subcellular localization of p24. We examined p24 localization in Xenopus intermediate pituitary melanotrope cells, which in black- and white-adapted animals are biosynthetically highly active and virtually inactive respectively. In addition, p24 localization was studied in Xenopus anterior pituitary cells whose activity is not changed during background adaptation. Using organelle fractionation, we found that in the inactive melanotropes and moderately active anterior pituitary cells of white-adapted animals, the p24-α, −β, −γ and −δ proteins are all located in the Golgi compartment. In the highly active melanotropes, but not in the anterior cells of black-adapted animals, the steady-state distribution of all four p24 members changed towards the intermediate compartment and subdomains of the endoplasmic reticulum (ER), most probably the ER exit sites. In the active melanotropes, the major cargo protein pro-opiomelanocortin was mostly localized to ER subdomains and partially co-localized with the p24 proteins. Furthermore, in the active cells, in vitro blocking of protein biosynthesis by cycloheximide or dispersion of the Golgi complex by brefeldin A led to a redistribution of the p24 proteins, indicating their involvement in ER-to-Golgi protein transport and extensive cycling in the early secretory pathway. We conclude that the subcellular localization of p24 proteins is dynamic and depends on the biosynthetic activity of the cell.
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December 2001
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Research Article|
November 26 2001
Localization of p24 putative cargo receptors in the early secretory pathway depends on the biosynthetic activity of the cell
Roland P. KUIPER;
Roland P. KUIPER
1
Department of Animal Physiology, Nijmegen Center for Molecular Life Sciences, University of Nijmegen, Geert Grooteplein Zuid 28, 6525 GA Nijmegen, The Netherlands
1To whom correspondence should be addressed (e-mail kuiper@sci.kun.nl).
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Gerrit BOUW;
Gerrit BOUW
Department of Animal Physiology, Nijmegen Center for Molecular Life Sciences, University of Nijmegen, Geert Grooteplein Zuid 28, 6525 GA Nijmegen, The Netherlands
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Karel P. C. JANSSEN;
Karel P. C. JANSSEN
Department of Animal Physiology, Nijmegen Center for Molecular Life Sciences, University of Nijmegen, Geert Grooteplein Zuid 28, 6525 GA Nijmegen, The Netherlands
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Jutta RÖTTER;
Jutta RÖTTER
Department of Animal Physiology, Nijmegen Center for Molecular Life Sciences, University of Nijmegen, Geert Grooteplein Zuid 28, 6525 GA Nijmegen, The Netherlands
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François van HERP;
François van HERP
Department of Animal Physiology, Nijmegen Center for Molecular Life Sciences, University of Nijmegen, Geert Grooteplein Zuid 28, 6525 GA Nijmegen, The Netherlands
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Gerard J. M. MARTENS
Gerard J. M. MARTENS
Department of Animal Physiology, Nijmegen Center for Molecular Life Sciences, University of Nijmegen, Geert Grooteplein Zuid 28, 6525 GA Nijmegen, The Netherlands
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Publisher: Portland Press Ltd
Received:
April 23 2001
Revision Received:
July 26 2001
Accepted:
September 21 2001
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London ©2001
2001
Biochem J (2001) 360 (2): 421–429.
Article history
Received:
April 23 2001
Revision Received:
July 26 2001
Accepted:
September 21 2001
Citation
Roland P. KUIPER, Gerrit BOUW, Karel P. C. JANSSEN, Jutta RÖTTER, François van HERP, Gerard J. M. MARTENS; Localization of p24 putative cargo receptors in the early secretory pathway depends on the biosynthetic activity of the cell. Biochem J 1 December 2001; 360 (2): 421–429. doi: https://doi.org/10.1042/bj3600421
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