Figure 3.

Sedimentation equilibrium analysis of synaptotagmin. Samples of synaptotagmin (3–10 μM) were centrifuged at multiple speeds (22,000, 27,000, and 32,000 RPM) as described in Materials and Methods. For clarity, only the absorbance scans taken at 27,000 RPM are shown. The resulting data from eight absorbance scans taken at 280 nm as a function of radial position and the corresponding fitted curve are shown in the lower panels, and the distribution of residuals are shown in the upper panels. The data were fit simultaneously to the following models: “single ideal species” model (A), “single non-ideal” species model (B), and “monomer-dimer ideal associative” model (C).