Figure 1.

Comparison between the T. brucei, the mouse (44), and the E. coli (45) class Ia R2 proteins. The ruler follows the conventionally used numbering of the E. coli R2 protein (45). Breaks in alignments are indicated with dots; breaks in the E. coli R2 protein sequence are indicated as dots in the ruler as well. Unless written out, every tenth residue is indicated as a cross in the ruler. Shaded residues are identical to the T. brucei R2 protein amino acid sequence. Residues mentioned in the text are indicated as the one-letter abbreviation. These are the iron ligands (D-84, E-115, H-118, E-204, E-238, H-241), the tyrosyl radical (Y-122), the residues in the hydrophobic pocket surrounding the radical (F-208, F-212, I-234), and the electron transport pathway residues (W-48, D-237, E-350, Y-356). E. coli R2 protein amino acid numbering is used. The part of the C terminus in the mouse R2 protein important for binding to the R1 subunit is indicated with five-point stars.