Fig. 2. (A,B) Western blots of sucrose gradient fractions and immunoprecipitates. (A) Western blots of axonemal extracts obtained from wild-type, pf18 and pf16 axonemes fractionated on 5-20% sucrose gradients. Blots were probed with our anti-calmodulin antibodies. Calmodulin sediments in three distinct peaks. The 12S peak of calmodulin is lacking or severely reduced in central pair-defective mutants. (B) Western blots of immunoprecipitates obtained from wild-type (wt) and pf6-2 axonemal extracts using our anti-PF6 antibodies. The blot was probed with anti-calmodulin antibodies. Calmodulin is precipitated by anti-PF6 antibodies from wild-type extracts.