FIG. 10.

Sucrose density gradient analysis of VP5–pUL80.5-H mixtures. Mixtures contained 10 μg of pUL80.5-H plus 10 μg of VP5 (a; ∼4:1 molar ratio of pUL80.5-H to VP5) and 30 μg of pUL80.5-H plus 18 μg of VP5 (b; ∼8:1 molar ratio). Gradients were prepared, and the fractions were analyzed by SDS-polyacrylamide gel electrophoresis as described in Materials and Methods. Centrifugation was done for 2.5 h at 26°C. The MW positions indicated in the top panel were calculated with reference to the sedimentation of protein standards by use of the equation of Martin and Ames (10). Note that VP5 migrated in the form of complexes with estimated MWs in the range of 200,000 to 600,000, and the most rapidly migrating peak of pUL80.5-H bound VP5 poorly. Vertical arrows indicate the position of VP5 migration in companion gradients in which no pUL80.5-H was present.