Article
- The EMBO Journal (2003) 22, 2645 - 2657
- doi:10.1093/emboj/cdg257
Subject Category:
Rabaptin-5
/rabaptin-4 serves as a linker between rab4 and 
1-adaptin in membrane recycling from endosomes
Magdalena Deneka1, Maaike Neeft1, Ioana Popa1, Masja van Oort1, Hein Sprong2, Viola Oorschot1, Judith Klumperman1, Peter Schu3 and Peter van der Sluijs1
- Department of Cell Biology and Institute of Biomembranes, University Medical Center, NL-3584 CX Utrecht, The Netherlands
- Max Planck Institute for Molecular Cell Biology and Genetics, D-01307 Dresden Germany
- Zentrum für Biochemie und Molekulare Zellbiologie, Biochemie II, Georg August Universität Göttingen, D-37073 Göttingen, Germany
Correspondence to:
Peter van der Sluijs, E-mail: pvander@knoware.nl
Received 29 July 2002; Accepted 28 March 2003; Revised 22 January 2003
Abstract
Rab4 regulates recycling from early endosomes. We investigated the role of the rab4 effector rabaptin-5
and its putative partner 
1-adaptin in membrane recycling. We found that rabaptin-5 forms a ternary complex with the 1–
1 subcomplex of AP-1, via a direct interaction with the 1-subunit. The binding site for 1-adaptin is in the hinge region of rabaptin-5, which is distinct from rab4- and rab5-binding domains. Endogenous or ectopically expressed 1- adaptin localized to both the trans-Golgi network and endosomes. Co-expressed rabaptin-5 and 1-adaptin, however, co-localized in a rab4-dependent manner on recycling endosomes. Transfection of rabaptin-5 caused enlarged endosomes and delayed recycling of transferrin. RNAi of rab4 had an opposing effect on transferrin recycling. Collectively, our data show that rab4-GTP acts as a scaffold for a rabaptin-5–1-adaptin complex on recycling endosomes and that interactions between rab4, rabaptin-5 and 1-adaptin regulate membrane recycling.
Keywords:
- 1-adaptin,
- endosomes,
- rab4,
- rabaptin-5,
- receptor recycling
