Figure 1: X-ray crystal structure of PGRMC1.

(a) Structure of the PGRMC1 dimer formed through stacked haems. Two PGRMC1 subunits (blue and green ribbons) dimerize via stacking of the haem molecules. (b) Haem coordination of PGRMC1 with Tyr113. Comparison of PGRMC1 (blue) and cytochrome b5 (yellow, ID: 3NER). (c) PGRMC1 has a longer helix (a.a.147–163), which is shifted away from the haem (arrow).