FIGURE 4.

Refilling of empty coat protein shells with mutant P22 scaffolding proteins. A mixture of 0.33 mg/ml of empty coat protein shells, 0.2 mg/ml of scaffolding protein, and buffer were incubated overnight at room temperature. The reactions were layered on 20% sucrose cushions and centrifuged to remove unbound scaffolding protein; the proteins in the pellet, which contained the refilled shells, were visualized with 12.5% SDS-PAGE. The lanes are labeled with the scaffolding protein used in the assay. The lane labeled WT (−) shells shows scaffolding protein incubated in buffer with no shells added does not pellet and the lane labeled shells shows the pelleting of the shells without added scaffolding protein.