Bex1 is essential for ciliogenesis and harbours biomolecular condensate-forming capacity

Emi Hibino, Yusuke Ichiyama, Atsushi Tsukamura, Yosuke Senju, Takao Morimune, Masahito Ohji, Yoshihiro Maruo, Masaki Nishimura, Masaki Mori

Research output: Contribution to journalArticlepeer-review


Background: Primary cilia are sensory organelles crucial for organ development. The pivotal structure of the primary cilia is a microtubule that is generated via tubulin polymerization reaction that occurs in the basal body. It remains to be elucidated how molecules with distinct physicochemical properties contribute to the formation of the primary cilia. Results: Here we show that brain expressed X-linked 1 (Bex1) plays an essential role in tubulin polymerization and primary cilia formation. The Bex1 protein shows the physicochemical property of being an intrinsically disordered protein (IDP). Bex1 shows cell density-dependent accumulation as a condensate either in nucleoli at a low cell density or at the apical cell surface at a high cell density. The apical Bex1 localizes to the basal body. Bex1 knockout mice present ciliopathy phenotypes and exhibit ciliary defects in the retina and striatum. Bex1 recombinant protein shows binding capacity to guanosine triphosphate (GTP) and forms the condensate that facilitates tubulin polymerization in the reconstituted system. Conclusions: Our data reveals that Bex1 plays an essential role for the primary cilia formation through providing the reaction field for the tubulin polymerization.

Original languageEnglish
Article number42
JournalBMC Biology
Issue number1
Publication statusPublished - Dec 2022


  • Bex1
  • Intrinsically disordered protein (IDP)
  • Juvenility-associated genes (JAGs)
  • Primary cilia
  • Tubulin polymerization

ASJC Scopus subject areas

  • Biotechnology
  • Structural Biology
  • Ecology, Evolution, Behavior and Systematics
  • Physiology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)
  • Plant Science
  • Developmental Biology
  • Cell Biology


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