Figure 10.

Nycodenz-gradient centrifugation of high-density AtSec21p antigen-containing membrane fraction from a Suc gradient. Microsomal membranes from cauliflower inflorescence were layered onto a discontinuous Suc-density gradient and centrifuged isopycnically. The membranes collecting on the 40%/55% (w/w) Suc interface (S1) were layered under a discontinuous Nycodenz gradient (see Methods) and recentrifuged until equilibrium conditions were obtained. TCA-precipitable proteins in the fractions collecting at the three interfaces (N1, 15%/25%; N2, 25%/30%; and N3, 30%/35%) were monitored by western blotting as described above (20 μg of protein per lane).