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- Title
Structural basis of Rab5-Rabaptin5 interaction in endocytosis.
- Authors
Guangyu Zhu; Peng Zhai; Jian Liu; Terzyan, Simon; Guangpu Li; Zhang, Xuejun C
- Abstract
Rab5 is a small GTPase that regulates early endosome fusion. We present here the crystal structure of the Rab5 GTPase domain in complex with a GTP analog and the C-terminal domain of effector Rabaptin5. The proteins form a dyad-symmetric Rab5-Rabaptin52-Rab5 ternary complex with a parallel coiled-coil Rabaptin5 homodimer in the middle. Two Rab5 molecules bind independently to the Rabaptin5 dimer using their switch and interswitch regions. The binding does not involve the Rab complementarity-determining regions. We also present the crystal structures of two distinct forms of GDP-Rab5 complexes, both of which are incompatible with Rabaptin5 binding. One has a dislocated and disordered switch I but a virtually intact switch II, whereas the other has its β-sheet and both switch regions reorganized. Biochemical and functional analyses show that the crystallographically observed Rab5-Rabaptin5 complex also exists in solution, and disruption of this complex by mutation abrogates endosome fusion.
- Publication
Nature Structural & Molecular Biology, 2004, Vol 11, Issue 10, p975
- ISSN
1545-9993
- Publication type
Academic Journal
- DOI
10.1038/nsmb832