The Journal of Cell Biology
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Introduction Thus, twoproperties,Ca John V.Kilmartin and geneticinteractions with spindle polebody duplication and anessentialfunctioninbuddingyeast Sfi1p hasconserved centrin-bindingsites changes inCa attached totheMTOC,whichcancontractinresponse the otherisasconstituentsofcontractilefiberswithinand 1981; Middendorpetal.,2000;Salisbury2002),and lished. OneisintheduplicationofMTOC(Byers, suggesting multipleroles.Twoclearroleshavebeenestab- different partsoftheMTOC(Levyetal.,1996),again organizing centers(MTOCs),andareoftenlocatedwithin ticular, centrinsareubiquitouscomponentsofmicrotubule- 1998; Arakietal.,2001;Pulvermuller2002).In processes (SchiebelandBornens,1995;Sullivanetal., calmodulin, haverolesinanumberofdifferentcellular Centrins areconservedcalmodulin-likeproteinsand,like Medical Research Council(MRC) ofMolecular Laboratory Biology, CambridgeCB22QH,UK on theCa moneme alsohaselasticpropertiesthatarenotdependent centrin (Maciejewskietal.,1999).Inaddition,thespas- 1975), hashomologytoEF-handdomainproteinssuch as 1999). Itsprincipleconstituent,spasmin(Amosetal., moneme (Weis-FoghandAmos,1972;Moriyamaetal., changes inCa related fibrousstructurethatalsocontractsinresponseto sensitive mutantsin body (SPB),where Cdc31pisalsolocalized. Temperature- these, Sfi1p,localizestothehalf-bridgeofspindlepole experiments toisolateCdc31p-bindingproteins.Oneof single Zdomainofprotein a with A, andusedinpull-down Cdc31p; centrin Key words: SPB;duplication; Sfi1p; Fax: 44-1223-412142.email:[email protected] Biology, HillsRd.,CambridgeCB2 2QH,UK.Tel.:44-1223-402242. J.V. Kilmartin,MRCLaboratory ofMolecular to correspondence Address http://www.jcb.org/cgi/doi/10.1083/jcb.200307064 The Journal ofCellBiology TheRockefeller University Press, 0021-9525 Article
cerevisiae crotubule-organizing centers. The entrins arecalmodulin-likeproteinspresentinmi-
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