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. Author manuscript; available in PMC: 2013 Dec 5.
Published in final edited form as: Structure. 2012 Dec 5;20(12):2003–2013. doi: 10.1016/j.str.2012.10.016

Figure 3. Constrained Refinement Minimizes Overfitting Effects and Produces Subnanometer Resolution Structures from Low-Dose Tomographic Tilt Series of GroEL.

Figure 3

Using particle projections extracted from the tilt series of GroEL, we compared the performance of orientation-fixed, traditional, and constrained projection-matching refinement in terms of agreement of assigned orientations with the tomographic constraints, value of the projection-matching objective function and resolution of reconstructions.

(A–C) Amplitude-corrected reconstructions obtained using orientation-fixed, traditional, and constrained projection-matching refinement, respectively.

(D) Comparison of orientations assigned to projections of the same single-particle by the three refinement strategies represented on the asymmetric triangle.

(E) Tracking of the projection matching objective function represented by Equation (1) for each of the three refinement strategies as a function of refinement iteration.

(F) FSC plots of reconstructions shown in (A)–(C) against X-ray model of GroEL. Color code in (D)–(F) is the same as in (A)–(C).