FIG. 4.

Cofractionation of 66K and 140K-derived proteins in chloroplast envelope fractions from TYMV-infected plants. Chloroplasts from TYMV-infected Chinese cabbage plants (I) and healthy control plants (H) were purified, lysed, and subjected to fractionation on a sucrose gradient. Equivalent amounts (7 μg) of proteins of the stroma (lanes 1 and 2), of the thylakoids (Thylak.) (lanes 3 and 4), and of the envelope membrane fractions (Env.) (lanes 5 and 6) were analyzed by SDS-8% PAGE. The gel was electroblotted onto a nitrocellulose filter, and the proteins were sequentially revealed by Western blotting with anti-66K and anti-140K antisera and NBT-BCIP (purple) and Fast red (red) substrates, respectively. Western blotting with anti-Toc75 antiserum and enhanced chemiluminescence detection were performed with 10 μg of the same samples as a specific marker of the envelope fractions. The positions of molecular weight markers (Biolabs) are indicated on the left (in thousands).