Fig. 1

Characteristics of the FAP45 and FAP52 null mutants. a Top: a transverse view of the 9+2 structure of the Chlamydomonas axoneme. Scale bar = 50 nm. Bottom: a magnified DMT. Arrowheads indicate MIPs. Major structures are colored; Outer dynein arm (ODA, magenta); Inner dynein arm (IDA, green); Dynein regulatory complex (DRC, purple); Radial spoke (RS, blue). IJ inner junction, OJ outer junction. Scale bar = 25 nm. b Western blot analyses of wild type, fap45, fap52, and fap45fap52 double mutant axonemes stained with various antibodies. FAP45 and FAP52 proteins were not detected in fap45 and fap52, respectively. Proteins essential for flagellar motility (ODA-IC2: outer dynein arm-intermediate chain 2; IDA-IC140: inner dynein arm-intermediate chain 140; IDA-p28: inner dynein arm-light chain p28; RSP1: radial spoke protein 1; DRC2 and 4: dynein regulatory complex 2 and 4; FAP20: inner junction protein of DMT) were not reduced in the mutants. c, d Axonemes from wild type and mutant Chlamydomonas crosslinked using EDC (zero-length crosslinker) were immunoblotted with anti-FAP45 (c) and anti-FAP52 antibodies (d). Filled arrowheads indicate the crosslinked product of FAP45 and FAP52 in a 1:1 ratio. The open arrowhead indicates the crosslinked product of FAP45 and tubulin. e–g Motility phenotypes of the mutants were assayed using the CLONA system. Swimming velocity and beat frequency were slightly reduced in fap45, whereas no significant reduction was observed in fap52. fap45fap52 showed a more severe phenotype than did fap45