Fig. 7.

Structural models of CD16A and related Fc receptors assembled with the FcεR1γ dimeric signaling adaptor. Centroid structures from the dominant cluster are shown for REMD assembly simulations of CD16A (A and D), FcεR1α (B and E), and CD64 (C and F) with FcεR1γ disulphide-linked dimers in model membranes (Materials and Methods for simulation and cluster analysis procedures). FcεR1γ is shown in purple, and receptor TM domains are shown in orange (CD16A), cyan (FcεR1α), or magenta (CD64). Side views (A–C) are shown with key interface residues in stick representation and colored green in receptor TM domains. The FcεR1γ intermolecular disulphide bond (at C2) and aspartic acid pair (D6) are also indicated. For each model, the boxed region is also shown in a view down the long axis of the trimeric complex (D–F), highlighting the key features of the proposed core TM packing region. Hydrogen-bonding interactions discussed in the main text are represented by yellow dashed lines. A pair of glycine (G13) residues in FcεR1γ (yellow ribbons) create a cavity that accommodates the phenylalanine side-chain in the core packing motif. All figures were prepared in MacPyMol.