The Recycling of ERGIC-53 in the Early Secretory Pathway
ERGIC-53 CARRIES A CYTOSOLIC ENDOPLASMIC RETICULUM-EXIT DETERMINANT INTERACTING WITH COPII*
- Felix Kappeler‡,
- Dieter R. Ch. Klopfenstein‡,
- Montserrat Foguet§,
- Jean-Pierre Paccaud¶‖ and
- Hans-Peter Hauri‡**
- From the ‡Department of Pharmacology, Biozentrum, University of Basel, CH-4056 Basel and ¶Department of Morphology, University of Geneva Medical Center, CH-1211 Geneva 4, Switzerland
Abstract
Further investigation of the targeting of the intracellular membrane lectin endoplasmic reticulum (ER)-Golgi intermediate compartment-53 (ERGIC-53) by site-directed mutagenesis revealed that its lumenal and transmembrane domains together confer ER retention. In addition we show that the cytoplasmic domain is required for exit from the ER indicating that ERGIC-53 carries an ER-exit determinant. Two phenylalanines at the C terminus are essential for ER-exit. Thus, ERGIC-53 contains determinants for ER retention as well as anterograde transport which, in conjunction with a dilysine ER retrieval signal, control the continuous recycling of ERGIC-53 in the early secretory pathway. In vitro binding studies revealed a specific phenylalanine-dependent interaction between an ERGIC-53 cytosolic tail peptide and the COPII coat component Sec23p. These results suggest that the ER-exit of ERGIC-53 is mediated by direct interaction of its cytosolic tail with the Sec23p·Sec24p complex of COPII and that protein sorting at the level of the ER occurs by a mechanism similar to receptor-mediated endocytosis or Golgi to ER retrograde transport.
Footnotes
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↵* This work was supported by the Kantons of Basel and the Swiss National Science Foundation.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵§ Present address: Novartis Pharma Ltd., CH-4002 Basel, Switzerland.
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↵‖ Supported by a grant from the Sir Jules Thorn Overseas Trust.
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↵** To whom correspondence should be addressed: Dept. of Pharmacology, Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland. Tel.: 41 61 267 2222 (or 2229); Fax: 41 61 267 2208; E-mail: Hauri{at}ubaclu.unibas.ch.
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↵1 The abbreviations used are: ER, endoplasmic reticulum; ERGIC, ER-Golgi intermediate compartment; PAGE, polyacrylamide gel electrophoresis; PBS, phosphate-buffered saline; endo H, endo-β-N-acetylglucosaminidase H; mAb, monoclonal antibody.
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↵2 M. Foguet, F. Kappeler and H.-P. Hauri, manuscript in preparation.
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↵3 F. Kappeler and H.-P. Hauri, unpublished results.
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- Received August 15, 1997.
- Revision received September 25, 1997.
