The outer dynd 皿 arm of ( Jntamydomenas flagella comp 盤 es three heaVy cha 血 s ( a 且 pha, beta , and ga a 〕 , eaCh With a metor activity . Their fu 皿 ctional dfference has 【 rot beeri wel !understood , altheugh studies usi 皿 g the prevlous 且 y is〕Lated mutants Odall 〔 La']king only the alpha Chain ) and Oda4− s7 ( Lacking on1y the beta chain ) have s 一 gested that they have disti 皿 ct ploperties . Here we have bohted a oew mutant , oda2 −6 , ladking only the ga 皿 ma chain , Unlike the ax −

more »

... Qf previously iso [ ated Oda2 mutant , which has mutation in the ga皿 ma heavy chain ge皿e and lacks the entire outer arm , the Oda2 − 6 axone 皿 e retains the alpha and beta chains , and has a novel 150kD peptide oorresponding to the N −ter皿 副 region of the gamma Chaiii . The phenobypic 〔 lifference between eda2 e 皿 d eda2 − fi suggests that the N − te皿 inal part of the gam 皿 a cbain iS important for the sta − ble assembly of thc outer a 口皿 . Thin −seCtion electron microscopy of the ada2 −6 axoneme , together with the ebservations with odall and od α 4 − s ? -defi 皿 es the apPrmximate Iocation80f the thr outa 【 atロ皿 heavy chaj 皿 s in the axonem 副 cross s tion. The swimming velocity a 皿 dflagellar beat frequency of oda2 −6 are close to these of o 面 2 and od α 」 − s7 , but significantly lower than those Qf wild type and αdall . Thus、 the k ef the functional gam 皿 u chain impairs the outer ar 皿 function as MllCh as does the lack of the beta Chain 、 and much more seriously than does the 1ack of the a工 pha chai1 . These resUlts suggest that the beta and gamlna heaVy chai 【 唄 play partieulaJ impo 「 te 皿 t 「oles in the ou £er arm function .