title: Together, the IFT81 and IFT74 N-termini form the main module for intraflagellar transport of tubulin.
abstract: The assembly and maintenance of most cilia and flagella rely on intraflagellar transport (IFT). Recent in vitro studies have suggested that, together, the calponin-homology domain within the IFT81 N-terminus and the highly basic N-terminus of IFT74 form a module for IFT of tubulin. By using Chlamydomonas mutants for IFT81 and IFT74, we tested this hypothesis in vivo. Modification of the predicted tubulin-binding residues in IFT81 did not significantly affect basic anterograde IFT and length of steady-state flagella but slowed down flagellar regeneration, a phenotype similar to that seen in a strain that lacks the IFT74 N-terminus. In both mutants, the frequency of tubulin transport by IFT was greatly reduced. A double mutant that combined the modifications to IFT81 and IFT74 was able to form only very short flagella. These results indicate that, together, the IFT81 and IFT74 N-termini are crucial for flagellar assembly, and are likely to function as the main module for IFT of tubulin.
authors.affiliation: Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Kubo
authors.affiliation: Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA Biology Department, Salem State University, Salem, MA 01970, USA.
authors.forename: Jason M
authors.initials: JM
authors.lastname: Brown
authors.affiliation: Biomedical Imaging Group, University of Massachusetts Medical School, Worcester, MA 01605, USA.
authors.forename: Karl
authors.initials: K
authors.lastname: Bellve
authors.affiliation: Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA.
authors.forename: Branch
authors.initials: B
authors.lastname: Craige
authors.affiliation: Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA.
authors.forename: Julie M
authors.initials: JM
authors.lastname: Craft
authors.affiliation: Biomedical Imaging Group, University of Massachusetts Medical School, Worcester, MA 01605, USA.
authors.forename: Kevin
authors.initials: K
authors.lastname: Fogarty
authors.affiliation: Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA.
authors.forename: Karl F
authors.initials: KF
authors.lastname: Lechtreck
authors.affiliation: Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA George.Witman@umassmed.edu.
authors.forename: George B
authors.identifier: 0000-0002-9497-9218
authors.initials: GB
authors.lastname: Witman
mesh_terms: D001692:Biological Transport / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D016825:Chlamydomonas reinhardtii / Q000235:genetics* / Q000378:metabolism; D002923:Cilia / Q000235:genetics / Q000378:metabolism; D005407:Flagella / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype; D011485:Protein Binding; D014404:Tubulin / Q000235:genetics* / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D014404:Tubulin
keywords: Chlamydomonas; Cilia; Ciliary assembly; Flagella; Microtubule; Tubulin binding