Figure 2. Sucrose density gradient analyses of solubilized chloroplast membranes after prRBCS import and chase.

(a) Chloroplasts were incubated with prRBCS for 20 min under import conditions, then re-isolated and further chased for 0–20 min. Membrane fractions from chloroplasts of each time point were solubilized and analyzed by sucrose density gradients. Filled triangles indicate the four fractions quantified in (b). An immunoblot of the large subunit of Rubisco (RBCL) is shown to indicate the position of endogenous Rubisco holoenzyme. Underlines mark the mature RBCS at the supercomplex fractions.

(b) Quantification of fractions representing distinct complexes from gels shown in (a). For each gel, the amount of prRBCS in fraction 19 (supercomplex) was set to 100% and the relative amounts of prRBCS in fractions 5 and 7 and mature RBCS in fraction 13 were then plotted.