FIG. 4.

Size fractionation of pm142-pm143 complexes and PKR on glycerol density gradients. NIH 3T3 cells were infected with MCMV (MOI of 3), and at 48 h postinfection cell lysates were prepared and centrifuged through 15 to 35% glycerol density gradients as described in Materials and Methods. Following centrifugation, fractions were collected from the bottom of the gradients, and the fractions were separated on polyacrylamide gels, transferred to PVDF membranes, and probed with a mixture of m142 and m143 antisera (A), after which the blot was stripped and reprobed with an anti-PKR antibody (B). Molecular size standards were size fractionated on a parallel gradient and then analyzed by polyacrylamide gel electrophoresis and Coomassie blue staining. The migration of the molecular size standards is indicated below panel B. Note that fractions 5 and 7 were lost during processing and that aliquots of the lysates (lys) prior to fractionation were included in the first and last lanes.