Figure 1.

Rca assembly mechanisms. (A) Representative FCS decays obtained with 50 nM labeled and increasing concentrations of unlabeled Rca. The concentrations in the inset represent total protein (labeled and unlabeled). (B–D) Comparison of experimental results and modeling. The solid circles are experimental values of the ratio of the apparent diffusion coefficient at each concentration (D_app) and the diffusion coefficient obtained at 50 nM (D₁). The horizontal red lines are placed at values of D_app/D₁ = k^−1/3 for k = 1, 2… 20, and represent the expected D_app/D₁ values for monomers, dimers, etc. The solid curves were calculated according to Model 1 (panel B), Model 2 (panel C), and Model 3 (panel D) with the K_d values from Table 1. The concentration profiles above each graph (panels B–D) represent the fractional subunit concentrations of the different oligomeric forms assumed to contribute to each model, as calculated from the total Rca concentration and the K_d values in Table 1.