Fig. 9.

Change in structure of minifilaments of recombinant AMII upon phosphorylation and dephosphorylation. Filaments of unphosphorylated WT in 10 mM imidazole (pH 7.0), 2.5 mM KCl, 1 mM ATP, and 1 mM MgCl₂ were phosphorylated by AMII heavy-chain kinase (pWT) and then were dephosphorylated by phosphatase (dpWT). (Upper) pWT: Phosphorylation converted staggered octamers (as shown in WT, Figs. 5 and 6) into a mixture of monomers (∼8%) and dimers (∼9%) (not shown) and, clumped tetramers (∼39%), and clumped hexamers (∼44%). (Lower) dpWT: Dephosphorylation reconverted pWT into a mixture of staggered tetramers (∼14%), hexamers (∼13%), and octamers (∼73%), as shown in paired images for each structure. (Scale bar, 100 nm.)