By evaluating the distance for the active site from the membrane, a prenyl substrate would be closest to the membrane if the final pose from replica 3 was selected for further evaluation. Other poses were judged to be implausible, as either a nascent prenyl chain would need to span a long distance in solution to reach the membrane, or the binding face would be occluded due to tetramerization. Thus, the pose from replica 3 formed the basis for further extending the prenyl product. Membrane contact analyses were repeated after the addition of an extended prenyl substrate (Figure ).