S-75 gel filtration and analytical ultracentrifugation of the sT-sRI complex. A: Elution profile of sT-sRI complex (□) and sRI (▪). S-75 standards are indicated by arrow heads, from left to right: 44, 29, 13.7, and 6.5 kDa. B: Coomassie-stained gel of samples collected from each gel filtration fraction in A. *: sRI and **: sT. C: Sedimentation velocity of sT-sRI complex (at various concentrations, see “Materials and Methods”).