FIG. 3.

Cofractionation of 66K and 140K-derived proteins in TYMV replication complexes. Replication complexes prepared from TYMV-infected Chinese cabbage plants were solubilized from membranes and centrifuged in a glycerol gradient that was subdivided into 18 fractions. (A) Samples of proteins from each fraction 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. The positions of molecular weight markers (Biolabs) are indicated on the left (in thousands). (B) The in vitro RdRp activity of each fraction was determined with TYMV RNA as a template. The activity is expressed as 10⁴ cpm of [³²P]UMP incorporated. Fractions obtained from healthy control plants were analyzed in parallel.