RSP16 depletion did not result in gross assembly defect of the RS complex. (A) Western analyses of axonemes using specific RSP antibodies (left and right) and an anti-spoke complex antibody (middle) revealed that in 12E8 and 13B3 (arrowheads), the RSPs in the spokehead (RSP1) and spokestalk were normal, whereas RSP16 was not detectable. These proteins were normal in entirely paralyzed flagella (12D5 and 13F3). The spokeless mutant pf14 was a negative control. RSP2 and 23, which were diminished as RSP16 in pf24 axonemes, were also normal in 12E8 (right). The blot was probed sequentially for RSP23 and RSP2. RSP12, positive control. (B) Western blots probed with anti-RSP2, anti-RSP3, and anti-spoke complex showed that RS in 12E8 KI extract sediment in 20S fractions in 5–20% sucrose gradient as wild-type spokes but distinct from the 12S spoke precursors.