title: The CSC proteins FAP61 and FAP251 build the basal substructures of radial spoke 3 in cilia.
abstract: Dynein motors and regulatory complexes repeat every 96 nm along the length of motile cilia. Each repeat contains three radial spokes, RS1, RS2, and RS3, which transduct signals between the central microtubules and dynein arms. Each radial spoke has a distinct structure, but little is known about the mechanisms of assembly and function of the individual radial spokes. In Chlamydomonas, calmodulin and spoke-associated complex (CSC) is composed of FAP61, FAP91, and FAP251 and has been linked to the base of RS2 and RS3. We show that in Tetrahymena, loss of either FAP61 or FAP251 reduces cell swimming and affects the ciliary waveform and that RS3 is either missing or incomplete, whereas RS1 and RS2 are unaffected. Specifically, FAP251-null cilia lack an arch-like density at the RS3 base, whereas FAP61-null cilia lack an adjacent portion of the RS3 stem region. This suggests that the CSC proteins are crucial for stable and functional assembly of RS3 and that RS3 and the CSC are important for ciliary motility.
authors.affiliation: Department of Cell Biology, Nencki Institute of Experimental Biology PAS, 02-093 Warsaw, Poland.
authors.forename: Paulina
authors.initials: P
authors.lastname: Urbanska
authors.affiliation: Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454.
authors.forename: Kangkang
authors.initials: K
authors.lastname: Song
authors.affiliation: Department of Cell Biology, Nencki Institute of Experimental Biology PAS, 02-093 Warsaw, Poland Department of Animal Physiology, Faculty of Biology, University of Warsaw, 02-096 Warsaw, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Joachimiak
authors.affiliation: Department of Cell Biology, Nencki Institute of Experimental Biology PAS, 02-093 Warsaw, Poland.
authors.forename: Lucja
authors.initials: L
authors.lastname: Krzemien-Ojak
authors.affiliation: Department of Cell Biology, Nencki Institute of Experimental Biology PAS, 02-093 Warsaw, Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Koprowski
authors.affiliation: Department of Biological Sciences, University at Buffalo, Buffalo, NY 14260.
authors.forename: Todd
authors.initials: T
authors.lastname: Hennessey
authors.affiliation: Department of Cell Biology, Nencki Institute of Experimental Biology PAS, 02-093 Warsaw, Poland.
authors.forename: Maria
authors.initials: M
authors.lastname: Jerka-Dziadosz
authors.affiliation: Department of Cell Biology, Nencki Institute of Experimental Biology PAS, 02-093 Warsaw, Poland.
authors.forename: Hanna
authors.initials: H
authors.lastname: Fabczak
authors.affiliation: Department of Cellular Biology, University of Georgia, Athens, GA 30602.
authors.forename: Jacek
authors.initials: J
authors.lastname: Gaertig
authors.affiliation: Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454 dwloga@nencki.gov.pl nicastro@brandeis.edu.
authors.forename: Daniela
authors.initials: D
authors.lastname: Nicastro
authors.affiliation: Department of Cell Biology, Nencki Institute of Experimental Biology PAS, 02-093 Warsaw, Poland dwloga@nencki.gov.pl nicastro@brandeis.edu.
authors.forename: Dorota
authors.initials: D
authors.lastname: Wloga
mesh_terms: D054468:Axoneme / Q000378:metabolism* / Q000648:ultrastructure; D002923:Cilia / Q000378:metabolism* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D015800:Protozoan Proteins / Q000502:physiology*; D013768:Tetrahymena / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D015800:Protozoan Proteins