Short-range coupling. (A) Short-range αM2M3 coupling at the ECD–TMD interface (PDB accession code 5KXI; mouse α subunit muscle AChR numbering). Lines: red, strong; white, significant. αP265 interacts strongly with αloop2 (Q48 and E45), αM2 (I260), and εloop9 (G183). (bottom) MCA values; blue bars are significant (≥0.6 kcal/mol). (B) Interactions across the fetal αγ TBS interface (PDB accession code 3WIP).