title: Luminal particles within cellular microtubules.
abstract: The regulation of microtubule dynamics is attributed to microtubule-associated proteins that bind to the microtubule outer surface, but little is known about cellular components that may associate with the internal side of microtubules. We used cryoelectron tomography to investigate in a quantitative manner the three dimensional structure of microtubules in intact mammalian cells. We show that the lumen of microtubules in this native state is filled with discrete, globular particles with a diameter of 7 nm and spacings between 8 and 20 nm in neuronal cells. Cross-sectional views of microtubules confirm the presence of luminal material in vitreous sections of brain tissue. Most of the luminal particles had connections to the microtubule wall, as revealed in tomograms. A higher accumulation of particles was seen near the retracting plus ends of microtubules. The luminal particles were abundant in neurons, but were also observed in other cells, such as astrocytes and stem cells.
authors.affiliation: Axonal Growth and Regeneration Group, Max Planck Institute of Neurobiology, 82152 Martinsried, Germany.
authors.forename: Boyan K
authors.initials: BK
authors.lastname: Garvalov
authors.forename: Benoît
authors.initials: B
authors.lastname: Zuber
authors.forename: Cédric
authors.initials: C
authors.lastname: Bouchet-Marquis
authors.forename: Mikhail
authors.initials: M
authors.lastname: Kudryashev
authors.forename: Manuela
authors.initials: M
authors.lastname: Gruska
authors.forename: Martin
authors.initials: M
authors.lastname: Beck
authors.forename: Andrew
authors.initials: A
authors.lastname: Leis
authors.forename: Friedrich
authors.initials: F
authors.lastname: Frischknecht
authors.forename: Frank
authors.initials: F
authors.lastname: Bradke
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Baumeister
authors.forename: Jacques
authors.initials: J
authors.lastname: Dubochet
authors.forename: Marek
authors.initials: M
authors.lastname: Cyrklaff
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000378:metabolism / Q000648:ultrastructure*; D001369:Axons / Q000378:metabolism / Q000648:ultrastructure; D002478:Cells, Cultured; D020285:Cryoelectron Microscopy / Q000379:methods; D003594:Cytoplasmic Granules / Q000378:metabolism / Q000648:ultrastructure*; D006367:HeLa Cells; D006624:Hippocampus / Q000378:metabolism / Q000648:ultrastructure*; D006801:Humans; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000378:metabolism / Q000648:ultrastructure; D008870:Microtubules / Q000378:metabolism / Q000648:ultrastructure*; D016501:Neurites / Q000378:metabolism / Q000648:ultrastructure; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure*; D009924:Organ Culture Techniques; D039904:Pluripotent Stem Cells / Q000378:metabolism / Q000648:ultrastructure; D051381:Rats
chemical_list: D008869:Microtubule-Associated Proteins