Possible communication pathways predicted based on highly correlated residues: residue 81 (top) in RBD-B1, residue 87 (middle) on RBD-A1, and residue 77 on RBD-A2 (bottom) and other residues mapped on structure of RBD-B1, RBD-A1, and RBD-A2 in their free state. Correlated residues with the covariance coefficient magnitude higher than 0.1 are labeled. Blue and red arrows show the possible communication pathway 1 and pathway 2 which were originally found for the unbound plexin-B1 RBD in the previous work.28,29