ABSTRACT
Lactoferrin (Lf), a member of the transferrin family protein, is an iron-binding protein that is known to interact with mammalian cells through a specific receptor. We examined binding of Lf to Jurkat human lymphoblastic T cell line (Jurkat cells) by far Western blotting, and found that bovine Lf and human Lf bound to the same protein components of Jurkat cells, and that pepsin digestion of Lf disrupts the sites responsible for binding to cellular proteins. We also found that the sugar chains of bovine Lf are not involved in binding between bovine Lf and Jurkat cells. Bovine Lf, bovine transferrin and ovotransferrin bound to the same proteins of Jurkat cells, which had molecular weights of about 35 kDa.
Subject(s)
Carrier Proteins/metabolism , Animals , Blotting, Far-Western/veterinary , Carrier Proteins/genetics , Cattle , Conalbumin/metabolism , Female , Humans , Jurkat Cells/metabolism , Lactoferrin , Receptors, Cell Surface/metabolismABSTRACT
Trypanosoma brucei, the causative agent of sleeping sickness in humans, requires transferrin (TF) for growth. Therefore, T. brucei has a TF receptor that allows it to obtain iron from TF. Lactoferrin (LF), a member of the TF family protein, is an iron-binding protein that is found in most biological fluids of mammals. LF has been shown to interact with some bacteria species by specific receptor-ligand binding. We examined the ability of T. brucei to bind bovine LF (bLF) by using a fluorescence test, streptavidin-biotin (SAB) microplate analysis, and far Western blotting using a biotin-streptavidin system. We found that bLF bound to components of T. brucei, and that bLF hydrolysate disrupted the sites responsible for binding to parasite proteins. Furthermore, bLF, human LF, bovine TF, and ovotransferrin bound same proteins of T. brucei, which exhibited molecular masses of 40 and 43 kDa. The N-terminal amino acid sequence of the 40 kDa bLF binding protein was identified as glyceraldehyde-3-phosphate dehydrogenase (GAPDH).
