Modification of CrKinesin-13. (A) CrKinesin-13 is modified during flagellar regeneration. 21gr cells were triggered to grow new flagella by pH shock (error bars, SD); (B) by transfer from agar plates into liquid medium (error bars, SEM); and (C) by washing into fresh medium cells whose flagella had shortened approximately to half length during incubation in 20 mM NaPPi (error bars, SEM). A flagellum on at least 50 cells was measured for each time point. In (A), pdf is a sample taken just before deflagellation; the T = 0 sample was taken immediately after deflagellation. (B, inset) Cells scraped from agar directly into sample buffer, and a sample of the same cells 5 minutes after washing into liquid medium; all of the CrKinesin-13 was in the unphosphorylated form in the agar-grown cells.