FIG. 4.

Binding of radiolabeled MHC-I molecules to insoluble curli aggregates. Curli aggregates (1 mg) were incubated with ¹²⁵I-labeled MHC-I molecules (2 × 10⁵ cpm). After incubation at room temperature, the aggregates were centrifuged and washed, and the radioactivity bound to the pellet was eluted by boiling in SDS-PAGE sample buffer. Samples were separated by SDS-PAGE (10% gel) under reducing conditions. Following electrophoresis, the gel was dried and exposed to X-ray film. Lane A, 2 × 10⁵ cpm of ¹²⁵I-labeled MHC-I molecules; lane B, radioactivity released from the curli pellet following incubation with 2 × 10⁵ cpm of ¹²⁵I-labeled MHC-I molecules. The 36- and 12-kDa bands represent the heavy and light chains, respectively, of MHC-I molecules. The migration of molecular mass markers is shown to the left.