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J Cell Sci. 2016 May 15;129(10):2106-19. doi: 10.1242/jcs.187120. Epub 2016 Apr 11.

Together, the IFT81 and IFT74 N-termini form the main module for intraflagellar transport of tubulin.

Author information

1
Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA.
2
Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA Biology Department, Salem State University, Salem, MA 01970, USA.
3
Biomedical Imaging Group, University of Massachusetts Medical School, Worcester, MA 01605, USA.
4
Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA.
5
Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA George.Witman@umassmed.edu.

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.

KEYWORDS:

Chlamydomonas; Cilia; Ciliary assembly; Flagella; Microtubule; Tubulin binding

PMID:
27068536
PMCID:
PMC5506485
DOI:
10.1242/jcs.187120
[Indexed for MEDLINE]
Free PMC Article

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