Figure 5.

Short- and mid-range structural and dynamics changes induced by the Leu → Pro exchange. A, 2D RMSD plot calculated for the C^α atoms of the EGF-1, EGF-2, and EGF-3 domains after superimposing onto the respective domains. All trajectories accounting for an aggregate simulation time of 2 × 3 μs were considered together in the analysis, excluding the first 200 ns of each trajectory and extracting frames at intervals of 100 ns. B, residue-wise mean backbone RMSF of the PSI domain after a mass-weighted fitting onto the starting structure. Error bars denote S.E. Blue and red curves represent the Leu³³ and Pro³³ isoforms, respectively; the two black lines delineate the AB loop (residues Glu²⁹–Pro³⁷). C, α_IIbβ₃ is shown in schematic representation and colored in light gray (with the exception of the PSI domain (green), EGF-1 domain (firebrick), and EGF-2 domain (marine)). Domains are labeled. The enlargement shows the location of the Leu → Pro exchange in the PSI domain within the genu interface of the β₃ subunit. Black dashed lines indicate distances computed in D with the distance values of the starting structure reported next to them. Residues Leu³³ (PSI domain), Ser⁴⁶⁹ (EGF-1 domain), and Gln⁴⁸¹ (EGF-2 domain) are depicted in ball-and-stick representation. D, mean distances between the C^α atoms of Leu³³/Pro³³ as well as Ser⁴⁶⁹ (EGF-1) and Gln⁴⁸¹ (EGF-2) calculated for the Leu³³ isoform (blue boxes) and the Pro³³ variant (red boxes) and measured in the crystal structure (Protein Data Bank code 3FCS; gray boxes). Error bars indicate mean ± S.E., and asterisks denote a significant difference (*, p < 0.05; ***, p < 0.0001) between the two isoforms of α_IIbβ₃.