FIG. 2.

Multimerization of pp28 through the self-interaction. (A) HFF cells were infected with HCMV (AD169) at an MOI of 0.1 and labeled with [³⁵S]Met-Cys and then chased in cycloheximide-containing medium for the indicated times as described in Materials and Methods. Cells were solubilized, loaded onto a 5 to 40% sucrose linear gradient, and sedimented by ultracentrifugation. Gradient fractions collected from the bottom, and each fraction was precipitated with anti-pp28 MAb and analyzed by SDS-PAGE. Note the presence of pp28 in fractions farther down the gradient in later chase intervals. (B) pp28 was transiently expressed in HK293 cells, and pp28 was fractionated in 5 to 40% sucrose gradient and analyzed as described above. The results shown as the percentage of total protein in each fraction. Note that with increasing chase interval (T = 0 versus 40 min) the pp28 migrated farther into the gradient, a finding consistent with increasing mass.