Functional analysis of an individual IFT protein: IFT46 is required for transport of outer dynein arms into flagella.
Intraflagellar transport (IFT), which is the bidirectional movement of particles within flagella, is required for flagellar assembly. IFT particles are composed of approximately 16 proteins, which are organized into complexes A and B. We have cloned Chlamydomonas reinhardtii and mouse IFT46, and show that IFT46 is a highly conserved complex B protein in both organisms. A C. reinhardtii insertional mutant null for IFT46 has short, paralyzed flagella lacking dynein arms and with central pair defects. The mutant has greatly reduced levels of most complex B proteins, indicating that IFT46 is necessary for complex B stability. A partial suppressor mutation restores flagellar length to the ift46 mutant. IFT46 is still absent, but levels of the other IFT particle proteins are largely restored, indicating that complex B is stabilized in the suppressed strain. Axonemal ultrastructure is restored, except that the outer arms are still missing, although outer arm subunits are present in the cytoplasm. Thus, IFT46 is specifically required for transporting outer arms into the flagellum.
Hou
Yuqing
Y
Department of Cell Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA.
Qin
Hongmin
H
Follit
John A
JA
Pazour
Gregory J
GJ
Rosenbaum
Joel L
JL
Witman
George B
GB
D000595:Amino Acid Sequence; D000818:Animals; D002465:Cell Movement; D016825:Chlamydomonas reinhardtii / Q000378:metabolism* / Q000648:ultrastructure; D003001:Cloning, Molecular; D017124:Conserved Sequence; D003598:Cytoskeletal Proteins; D004398:Dyneins / Q000378:metabolism*; D005407:Flagella / Q000378:metabolism* / Q000648:ultrastructure; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D021381:Protein Transport; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D016415:Sequence Alignment
D003598:Cytoskeletal Proteins; C519209:IFT46 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D015800:Protozoan Proteins; D004398:Dyneins