The N- and C-terminal domains of some plant GLB3 proteins are shown in
A, with a portion of the central region connecting them
aligned with other Hbs in B. In A, the
full C-terminal portion of cotton GLB3 is not shown, as it has not been
determined. Shown in B is a structure-based sequence
alignment of plant GLB3 proteins from A. thaliana,
barley, barrel medic, and cotton, with 2-on-2 Hbs from microorganisms
(2) and plant Hbs that have a myoglobin-like fold (11). Boxed regions
denote α-helical regions in the structures of rice GLB1;1 and the
2-on-2 Hb of P. caudatum. Residues conserved between
M. tuberculosis GLBO and GLB3 proteins are highlighted.
The proximal (F8) and distal (E7) residues are marked with a star, and
the helix designations for the beginning and end of the central domain
are given.