Stereo photos of an area of the electron density map of cytochrome b5, corresponding to the amino acid positions 9, 12 and 13. A model with the amino acids Ile-Glu in the positions 12 and 13 is overlaid. In the originally published sequence, the positions 12 and 13 are given as Glu and Ile. This does not correspond to the electron density distribution and had consequently to be corrected (F. S. MATHEWS et al., Washington University, School of Medicine, 1971).
