Interestingly, while we do observe some association between the N-terminus of our truncated NgBR and the membrane (Figure ), it is from a helix stretching from residue 76 to 93, which does not map onto either of the proposed membrane binding helices. The proposed helix stretching from 117 to 135, which is included in the truncated structure, does not appear to make membrane contact. While it is perfectly feasible that the NgBR N-terminus region could connect the protein to the ER membrane without significant orientational constraints, the reduction in membrane contact in our double mutant studies suggests that multiple membrane anchors are needed for function.