Lactoferrin and transferrin: functional variations on a common structural framework.

Lactoferrin shares many structural and functional features with serum transferrin, including an ability to bind iron very tightly, but reversibly, a highly-conserved three-dimensional structure, and essentially identical iron-binding sites. Nevertheless, lactoferrin has some unique properties that differentiate it: an ability to retain iron to much lower pH, a positively charged surface, and other surface features that give it additional functions. Here, we review the structural basis for these similarities and differences, including the importance of dynamics and conformational change, and specific interactions that regulate iron binding and release.