FIG 4.

Heptad repeat discontinuity (stutter) of the σ1 coiled coil. The trimeric σ1 protein is shown in blue, red, and yellow. For a sequence comparison of the stutters between different reovirus serotypes, see Fig. 2A. (A) T1L σ1 d-a layer formation between E150 and V151. The view is along the 3-fold axis of the molecule. (B) Side view of the same region. T1L σ1 residue R153 forms a salt bridge with E150 and D155. (C) T3D σ1 d-a layer formation between I154 and Q155. The view is along the 3-fold axis of the molecule. (D) Side view of the same region. T3D σ1 residue Q155 also interacts with R150 of an adjacent chain.