1tu3

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Template:STRUCTURE 1tu3

Crystal Structure of Rab5 complex with Rabaptin5 C-terminal Domain

Overview

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-Rabaptin5(2)-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 beta-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.

About this Structure

1TU3 is a Protein complex structure of sequences from Homo sapiens. Full crystallographic information is available from OCA.

Reference

Structural basis of Rab5-Rabaptin5 interaction in endocytosis., Zhu G, Zhai P, Liu J, Terzyan S, Li G, Zhang XC, Nat Struct Mol Biol. 2004 Oct;11(10):975-83. Epub 2004 Sep 19. PMID:15378032 Page seeded by OCA on Sat May 3 10:21:55 2008