Human lactotransferrin: molecular, functional and evolutionary comparisons with human serum transferrin and hen ovotransferrin.

In this review article, human lactotransferrin is compared to human serum transferrin and hen ovotransferrin. For the first time the possibility of a 6-fold internal homology of the transferrins is raised: a scheme in which 6 domains are defined is reported; two of them with the highest homology seem to be implicated in the 2 iron binding sites of each transferrin. The location of the disulfide bridges of the 3 transferrins and of their prosthetic sugar groups is discussed: some not yet described half-cystine containing lactotransferrin peptides are indicated.