title: A conserved CaM- and radial spoke associated complex mediates regulation of flagellar dynein activity.
abstract: For virtually all cilia and eukaryotic flagella, the second messengers calcium and cyclic adenosine monophosphate are implicated in modulating dynein- driven microtubule sliding to regulate beating. Calmodulin (CaM) localizes to the axoneme and is a key calcium sensor involved in regulating motility. Using immunoprecipitation and mass spectrometry, we identify members of a CaM-containing complex that are involved in regulating dynein activity. This complex includes flagellar-associated protein 91 (FAP91), which shares considerable sequence similarity to AAT-1, a protein originally identified in testis as an A-kinase anchor protein (AKAP)- binding protein. FAP91 directly interacts with radial spoke protein 3 (an AKAP), which is located at the base of the spoke. In a microtubule sliding assay, the addition of antibodies generated against FAP91 to mutant axonemes with reduced dynein activity restores dynein activity to wild-type levels. These combined results indicate that the CaM- and spoke-associated complex mediates regulatory signals between the radial spokes and dynein arms.
authors.affiliation: Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA.
authors.forename: Erin E
authors.initials: EE
authors.lastname: Dymek
authors.forename: Elizabeth F
authors.initials: EF
authors.lastname: Smith
mesh_terms: D000818:Animals; D054468:Axoneme / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000737:chemistry*; D002465:Cell Movement; D016825:Chlamydomonas reinhardtii / Q000378:metabolism*; D004398:Dyneins / Q000737:chemistry* / Q000378:metabolism; D005407:Flagella / Q000737:chemistry* / Q000378:metabolism; D047468:Immunoprecipitation; D013058:Mass Spectrometry; D008870:Microtubules / Q000378:metabolism / Q000502:physiology*; D008954:Models, Biological; D009154:Mutation; D010455:Peptides / Q000737:chemistry; D014018:Tissue Distribution
chemical_list: D002147:Calmodulin; D010455:Peptides; D004398:Dyneins; D002118:Calcium