Figure 4
From: Structural basis of GC-1 selectivity for thyroid hormone receptor isoforms
Bleicher4.png. Conformational variability of the Arg228 (hTRα) and Arg282 (hTRβ) residues as observed from molecular dynamics simulations. (a) The greater flexibility of the Arg228 side chain relative to the Arg282 side chain can be observed by the larger RMS deviations. This flexiblity results from weaker anchoring of this side chain in hTRα. (b) Two binding modes can be distinguished if one computes the CZ-C20 distance. (c) The snapshots of Arg282 show practically the same productive conformation, locked in place by the strong interaction with the Asn331 side-chain. (d) Asn331 (hTRβ) to Ser277 (hTRα) substitution removes these conformational restrains and allows Arg228 to sample a much wider range of conformations. The non-productive conformations encountered in the simulations resemble closely the non-productive conformations of Arg228 found in the crystallographic structures.