Medium Chains of Adaptor Complexes AP-1 and AP-2 Recognize Leucine-based Sorting Signals from the Invariant Chain*
- From the Division of Molecular Cell Biology, Department of Biology, University of Oslo, P. O. Box 1050 Blindern, 0316 Oslo, Norway
Abstract
Interactions between tyrosine- and leucine-based sorting signals in the cytoplasmic tails of transmembrane proteins and adaptor complexes AP-1 and AP-2 are believed to be the first step in the formation of clathrin-coated vesicles that deliver these proteins to their destination. Medium chains of AP-1 and AP-2 have been reported to interact with tyrosine-based sorting signals in a number of in vitro assays. In the present study we found that recombinant medium chains could interact with leucine-based sorting signals from the cytoplasmic tail of the invariant chain. Medium chains may therefore be responsible for the proper recognition of both tyrosine and leucine sorting signals by AP-1 and AP-2 complexes.
Footnotes
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↵* This work was supported by the grants from the Norwegian Cancer Society and the Norwegian Research Council (to O. B. and D. G. R.).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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↵‡ To whom correspondence should be addressed:P. O. Box 1055, Blindern, University of Oslo, 0316 Oslo, Norway. Tel.: 47-22855787; Fax: 47-22854605; E-mail: obakke{at}bio.uio.no.
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↵1 The abbreviations used are: CCV, clathrin-coated vesicles; AP, adaptor protein complex; Ii, invariant chain; ECL, enhanced chemiluminescence; PVDF, polyvinylidene difluoride; BSA, bovine serum albumin.
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↵2 Bremmes, T., Lauvrak, V., Lindqvist, B., and Bakke, O. (1998) J. Biol. Chem. 273, in press.
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↵3 A. Motta, personal communications.
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- Received November 18, 1997.
- Revision received January 5, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
