FIG. 2.

Fractionation by sucrose density gradient centrifugation. The preparation of basal bodies was applied to a 20 to 60% (wt/wt) stepwise sucrose gradient in TEC (TE buffer containing 0.5% CHAPS). After centrifugation at 72,000 × g for 90 min at 4°C, the gradient was divided into 20 fractions from the top to the bottom. For observation by electron microscopy, basal bodies in some fractions were collected by ultracentrifugation at 100,000 × g for 30 min and the pellet was resuspended using TEC. The proteins in each fraction were separated by SDS-PAGE and detected by immunoblotting using anti-MotY and anti-FliG antibodies. HBB indicates the basal body fraction before the sucrose density gradient centrifugation. The underlined fraction was used for electron microscopy.