FIGURE 3.

Multimer analysis by gel filtration and cross-linking. A–I, multimer formation of B2′B3 or B3 was evaluated by gel filtration. In these profiles, multimer formation was determined by measuring the elution times (min) of these proteins from a Superose 6 10/300 GL column. Protein elution was monitored by measuring absorbance at 280 nm (absorbance units at 280 nm (AU_{280 nm})). The retention times of the standards are shown at the top of each panel. J, BS³ cross-linking was performed as described under “Experimental Procedures,” and 1.5% SDS-AGE was used to separate cross-linked proteins. The mutant forms are described in the legend to Fig. 1C.