Figure 6.

CP is coenriched with several membrane-bound compartments in the microsomal fraction. Microsomal (P₂₀₀) membrane fractions were separated on an isopycnic 20% to 50% (w/v) linear Suc gradient. Equal volumes of protein fractions collected from the gradient were separated on SDS-PAGE gels, blotted, and probed with antibodies against the following: CPA and CPB; actin; cis-Golgi, α-1,2-mannosidase; trans-Golgi, RGP1; plasma membrane, H⁺-ATPase; ER, Sec12; tonoplast, V-ATPase; mitochondrial outer membrane porin 1, VDAC1; trans-Golgi network, AtSYP41 and RabA4; and peroxisome, catalase. Protein names and sizes are indicated on the left and right, respectively. The entire gradient, fractions 1 to 26, required several gels and membranes for probing with each antibody. Separation between the individual blots or membranes comprising the full gradient is not shown on the figure, for clarity of presentation. Mann, Mannosidase; MITO, mitochondria; Perox, peroxisome; PM, plasma membrane; TGN, trans-Golgi network.