Fig. 3.

Covariance matrix for the fluctuations of the C_α atoms in wild type DHFR and various mutants. Yellow and red regions indicate that the C_α atoms move in a concerted way (positively correlated movements), and dark blue means they move opposite to each other (anticorrelated movements). The scale goes from −0.6 (dark blue) to 1 (red). We note that we get the same qualitative picture for the correlated motions if all heavy atoms are included in the calculation of the covariance matrix. (Figure 3 of Rod TH, Radkiewicz JL, Brooks III CL (2003) Proc. Nat. Acad. Sci. USA 100: 6980, Copyright © 2003, National Academy of Sciences USA)