The top picture is a labeled ribbon drawing of the first intact antibody (IgG2A) ever crystallized. The antibody is assymetric, reflecting its dynamic character. There are two local dyads in the molecule. One relates the heavy chains in the Fc, the other relates the constant domains of the Fabs. The bottom picture is the crystal from which the above structure was deduced. The longest edge of this crystal is roughly 1 mM across. For more information on this antibody, see:

or the PDB file (1IGY).