A ligand may be fully compatible with a receptor, binding with both sections.
A ligand may only be compatible with one of the two receptor parts, while the other part remains incompatible with the ligand.
A ligand may only be compatible with the second of two receptor parts, while the other part remains incompatible with the ligand.
A ligand may be fully incompatible with receptor, and fail to bind with either of the two sections.
A ligand may be fully incompatible with receptor, and fail to bind with either of the two sections.