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Updated: Jan 26, 2026

Assembly and Characterization of Polyelectrolyte Complex Micelles
Published on: March 2, 2020
Binding of IFT22 to the intraflagellar transport complex is essential for flagellum assembly
Stefanie Wachter1, Jamin Jung2, Shahaan Shafiq2
1Department of Structural Cell Biology, Max Planck Institute of Biochemistry, Martinsried, Germany.
Abstract:
Intraflagellar transport (IFT) relies on motor proteins and the IFT complex to construct cilia and flagella. The IFT complex subunit IFT22/RabL5 has sequence similarity with small GTPases although the nucleotide specificity is unclear because of non-conserved G4/G5 motifs. We show that IFT22 specifically associates with G-nucleotides and present crystal structures of IFT22 in complex with GDP, GTP, and with IFT74/81. Our structural analysis unravels an unusual GTP/GDP-binding mode of IFT22 bypassing the classical G4 motif. The GTPase switch regions of IFT22 become ordered upon complex formation with IFT74/81 and mediate most of the IFT22-74/81 interactions. Structure-based mutagenesis reveals that association of IFT22 with the IFT complex is essential for flagellum construction in Trypanosoma brucei although IFT22 GTP-loading is not strictly required.
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