The structure of the molybdenum cofactor carrier protein from Chlamydomonas reinhardtii (PDB 2IZ6). Left, the overall architecture of the (α2)2 tetramer, with one α2 dimer in blue and green, and the other in gray and yellow. Right, an enlargement of the gray subunit at left with the region identified as the possible cofactor binding site delimited by the regions in red, including Met 60 and Pro 69.