The Journal of Cell Biology
JCB
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anterograde IFT. Fullyassembledradial spokes,detached cell body, beforebeingtransported totheflagellar tipby Radial spokeswerefoundtobepartiallyassembledinthe consisting of22polypeptides,aspotentialcargoforIFT. Here, weexamineradial spokes,axonemalsubunits transport flagellarprecursorstothe tipforassembly. eukaryotic flagellaand cilia.OnepositedroleofIFTisto Hongmin Qin,Dennis R.Diener, Stefan Geimer, Douglas G.Cole,andJoel L.Rosenbaum transport, andassemblyofflagellarcomponentswouldbe et al.,2001).Onemechanismthatwouldsimplifytargeting, (radial spokeprotein[RSP]1–22;Pipernoetal.,1981;Yang ent polypeptides(King,2000)andradialspokescontain22 subunits. Forexample,outerdyneinarmscontain16differ- tenance inthemature,full-lengthflagellum. not onlyduringflagellargrowth,butalsoformain- fore, mustbetransportedtotheflagellartipforassembly, to thecellbody flagellar precursors tothetipandturnover products Intraflagellar transport (IFT)cargo:IFTtransports Key words: cilia; intraflagellar; transport; kinesin;radialspoke transport; Key words: cilia;intraflagellar; and Biochemistry,UniversityofIdaho, Moscow,ID83844-3052. D.G. Cole’spresentaddressisDept. ofMicrobiology,MolecularBiology Gyrhofstrasse 15,50931Cologne,Germany. S. Geimer’spresentaddressisUniversity ofCologne,BotanicalInstitute, 5059. email:[email protected] sity, NewHaven,CT06520.Tel.:(203)432-3472.Fax:432- Address correspondencetoJoelRosenbaum,MCDBDept.,YaleUniver- The 250 to thetipandremovalofdiscardedflagellarproteins. tip oftheflagellumrequiresperpetualdeliveryprecursors assembly anddisassemblyofaxonemalcomponentsatthe Rosenbaum, 2001;SongandDentler,2001).Thecontinuous are constantlyturningover(Stephens,1997;Marshalland structure inwhichthemicrotubulesandappendedproteins The flagellum,inspiteofitsapparentstability,isadynamic ofMolecular,Department Cellular, andDevelopmental Biology, Yale University, New Haven, CT06520 Introduction http://www.jcb.org/cgi/doi/10.1083/jcb.200308132 The Journal ofCellBiology
TheRockefeller University Press, 0021-9525 tubules andisrequiredforassemblymaintenanceof of multisubunitproteinparticlesalongaxonemalmicro- ntraflagellar transport (IFT)isthebidirectionalmovement
Article Many axonemalcomponentsarecomprisedofmultiple